First of all my apologies to Marcus at Lausitz Aviation who's image i stole to create this masterpiece :o) - thank you Marcus for your kindness.    And I also have to add that no two cockpits are the same for various reasons i.e. expectations versus budget versus skill level.   I did this my way for the reasons I did and by sharing my experiences, just maybe if you don't agree with the way I have done something, it just might give you an idea of your own.   And of course I have built this as a fun thing and not as an obsession. The fact it turned out pretty damn good is a bonus. I don't pretend to be a Jonathon Richardson or a Matt Ford, but Jeez do I have fun :o)
Well how do you get it all working. In a nutshell it's not so bad if you plan it all. What i have done in the above diagram is to try to group everything into colored categories.  This will help me to explain where the display comes from or where the annunciator get's it power from or where the switch sends it signal.
If you look at the above diagram, the colour coding is as follows......
RED = FSXPAND ( www.flyware.nl ). BLUE = PMDG ( www.precisionmanuals.com/ ) GREEN = Own Circuit
YELLOW = CPFLIGHT ( www.cpflight.com )  MAGENTA - L =LAUSITZ ( www.lausitzaviation.com )  H = HISPAPANELS  ( www.hispapanels.com ) and X = Experimental that is i am playing around with some ideas.

Right if you have the rest of your life free, i'll try to explain what goes on in a little more detail,especially the Annunciator Sources which will be at the end of the page.

PMDG The most important source of information for the pilot is the PFD where all flight parameters are displayed. Flight Mode Annunciators, Heading and Track Information, Rate of Climb or Descent, MCP Selection Information - it's all contained here.  Then there is the ND where all the Navigation Map, Rose, VOR & ILS Indicators and Route Information is displayed.  The PMDG instrumentation is really good and if you buy the Aircraft, you get it for free, now that's value :o)
So how did i get these displayed.  I created a second cockpit view in FS and re-wrote the PMDG panel file for the aircraft model i use in the cockpit. I also deleted the Panel Background bitmap because i didn't need it. This then meant that i could close the view of the outside world on the window that contained my panel.   This panel window was moved to a second monitor whereby adjusting the position and size of the PFD & ND gauges, i could place them exactly where i wanted them to fit the screen frames in my MIP. I initially was using 17" monitors, but these have been upgraded to 19" so they fill the display frames.  The second video output is run thru a 'Y' cable so it feeds 2 monitors, one for the captain and one for the F/O.

FSXPAND The Centre EICAS display, the 3 Standby Instruments and the Rotary Flaps Gauge are all generated using FSXpand.  This is one of the best pieces of programming that i use in my setup. It is a 2 part program developed by Gert Heijnis at www.flyware.nl .   FSXpand (the server) lives on the FS machine and communicates with FSClient which I have on a separate networked computer.  Part of the package is a 737NG Eicas panel (ok it doesn't fit your MIP) which can be resized and configured to fit any monitor/screen resolution/display position.   I configured one of the panels to give me the Eicas, AI - ALT - HSI and the Rotary Flaps Gauge.   Then there is the Panel Switching function which Gert has included in the Joysticks Menu on the client machine.    This has allowed me to build 5 different Eicas screens.  Each of the 5 Screens contains the 3 standby Instruments and the Rotary Flaps Gauge as they are displayed irrespective of whether the Eicas is operational or not.        But the Eicas element is different in each Screen.   I have OFF - Normal - Engine Primary with Text Annunciation - Condensed and INOP.
With FSXpand allowing functions via a Joystick Axes Input, i stripped out an old Saitek Joystick and replaced the existing potentiometers with new Rotary one's.  This allowed me to place these pots in the Display Units Control Panel on the MIP. One on the Capt's side (using the X Axis) and one on the F/O side (using the Y axis).  So we can now change the Eicas Screen to whatever we want at any phase of flight.  And the added bonus is that FSXpand will now allow multiple clients, so I will look at repeating the above for the lower Eicas screen ( i found a cheap 10" monitor on e-bay :o).
Talking about Joystick Axes inputs thru FSXpand and FSClient, the 3rd Axis (Z) on my 'modified' Joystick Card is used for Ground Steering.   I have used a Multi Turn potentiometer (basically a normal Pot fitted with a small gearbox which needs 10 turns to take the Pot all the way thru it's range) and assigned it to the rudder because we all know that the rudder and the nose wheel are connected .  The wiper on the Pot is wired thru the Ground Steering Switch (which can be isolated to prevent erroneous inputs).  I am also experimenting with the Auto Brake using both FSXpand and FSUIPC at the moment  -  WATCH THIS SPACE.

CPFLIGHT I have the CPFlight MCPEX1.  In addition to the functions described on the MCPEX1 page, it also allows for certain inputs and the output of certain signals and annunciators which are detailed at the end of the page.

H = HISPAPANELS  OK I use several items from Manolo at www.hispapanels.com on the MIP.  I have the LEVEL and BALANCE Gauge just above the 3 standby Instruments and also the Brake Pressure Gauge to the right of the Gear Annunciators.  These are both 'Dummy' Gauges to fill the Holes in the MIP.   And finally I have the Chronometers on both the Captain and First Officer Sides.  These again are dummies because although you can get them up and running with Digital Readouts, I just haven't got the time right now, maybe next year.   They are actually running as Clocks and here's how to do it real cheap.  Apart from the actual Plates, it cost me GB£2 (about 2.80 euros each)

L = LAUSITZ The mechanical Gear lever I originally got from the LUCHVAART HOBBY SHOP in Holland, but it has been discontinued.   Since that time, Marcus Menzel at Lausitz Aviation has started production of a lever to compete with the existing products available.   I have seen this lever real close up and have no hesitation in linking to Marcus site.  He is a very dedicated, small manufacturer of extremely high quality products.

X = EXPERIMENTAL There are several items on the MIP which are still in the experimental Stage.   I think I may have worked around the Autobrake Problem using FSUIPC (v3.70).  FSUIPC allows you to assign multiple actions to a single Joystick Axis Input.  So what I have done is this.  On my TQ, I have 2 Thrust Reverse levers.  In the FSUIPC Axis Assignment Menu I have assigned the left lever to both apply Reverse Thrust on engine 1 and apply left braking. The second lever is assigned to apply Reverse Thrust to Engine 2 and apply right braking.   Reverse thrust is set to idle at a given speed when landing and the call 'Manual Braking' is made. So on touchdown, the Reverse Thrust Levers are pulled back and we get all brakes coming on as well.  When the levers are returned to the OFF position, manual braking is then used.   I have wired the wiper to these pots into the Autobrake Switch so that the Autobrakes have to be set for the Action to take place.    More experiments are taking place with other systems as we speak :o))

ANNUNCIATORS In this paragraph, I hope to explain how each of the Annunciators should and actually does illuminate.  I intend to describe how I have also actioned that condition.
LANDING GEAR ANNUNCIATORS Condition - Each wheel set has a Green and Red Annunciator.  That's 3 sets of lights.   When the Gear is in transit, the Red Lights should illuminate. When the Landing Gear is up, all lights should be off.     When the Landing Gear is Down, all 3 Greens should be illuminated.  Solution The Landing Light Annunciators are powered thru the CPFlight MIP737 Board which switches them on cue.  Refer to the CPFlight documentation for how to do this.
YAW DAMPER  Condition When the Yaw Damper is switched off, both the Yaw Damper Annunciator on the Overhead and the MIP will be illuminated.  when the YD is switched ON both the annunciators will be off.    Solution  The Yaw Damper Annunciator (Orange) is powered from the Overhead Panel Yaw Damper Switch which directly controls the PMDG Yaw Damper thru Key2Mouse.             So when the PMDG Yaw Damper Switch is set on, both the Overhead and MIP Yaw Damper Annunciators are out.       And vice-versa.
SPEEDBRAKE ARMED/SPEEDBRAKE EXTENDED  Condition - When the Speedbrake Lever is moved to the Armed position, the Speedbrake 'Armed' annunciator (Green) should be illuminated and when the Speedbrakes are Up (either Automatically or Manually in the Flight Detente position) the 'Armed' Light should be extinguished and the (Orange) 'Speedbrakes Extended' light on the F/O side should illuminate.    Solution - What I did here was to fit 2 micro switches to the inside of the TQ cabinet which are actioned by the lever. The lever needs to be calibrated accurately  so correct illumination occurs at every lever position.     CIRCUIT DIAGRAM & EXPLANATION.
TEST/RECALL CIRCUIT I have built in a Test/Recall Circuit where by when the Test/Recall Button is pressed, every LED on the MIP/GLARESHIELD/OVERHEAD Lights up.  It looks really impressive :o)   This is accomplished by powering the LED from 2 sources.  First is the actual switching source e.g. the Gear Lights are switched from the MCPEX1 and a second source which is the test circuit.    The two circuits are kept separate by the use of diodes, so one circuit cannot interfere with or feed power into the other circuit.   It's really easy to do, let me show you here in the  CIRCUIT DIAGRAM AND EXPLANATION.