Having purchased the CPFlight MCP as the 'Autopilot of Choice' it seemed logical to also buy the MCPEX1 Expansion Board to complement this amazing piece of equipment.
The MCPEX1 duly arrived. It is very well made, very simple to connect too and in all fairness is very easy to setup and get running.   All you need to do is connect the board to the MCP with a Data Cable and you're up and running once the CPFlightTools software has been installed.    The CPFlight 'system', that is all the pieces of CPFlight Hardware you have attached to your computer, communicate with FS via FSUIPC and the FS_COM utility.
Lets assume that  you have installed the software.
In the package comes a small setup program called MCP_CONFIG.  It is this utility that you use to setup the inputs and outputs from the MCPEX1 using a basic 'What You See Is What You Get' menu system (which you can add to when you get more experienced).                  Best advice is GET & READ THE MANUAL so you understand what type of inputs and outputs are possible with the MCPEX1.

This is what i am doing on the PMDG737 with my MCPEX1 board

PARKING BRAKE - (INPUT) The Parking Brake switch is connected to Input A1 and assigned in MCP_CONF to the Parking Brake.  When the switch is closed, FS_COM sets the Brake to ON and when it is opened, the Brake is set OFF.  (OUTPUT)    One of the Digital Outputs has been assigned to the Parking Brake, so when the Brake is set, the Red Indicator on the TQ Illuminates.

IDLE/CUTOFF LEVERS - (INPUT) My Symulatory TQ has microswitches fitted to the Idle/Cutoff Levers. These are connected to two Digital Inputs on the MCPEX1 and then assigned to Eng 1 and Eng 2 Fuel Valve respectively. The PMDG responds to the 'Toggle Fuel Valves' command in FSUIPC.  I then found out that these offsets are 'writeable'.  3590 for the Eng 1 Fuel Valve and 3954 for Eng 2.  The parameters are 0 for closed and 1 for open.  Now we have an accurate On/Off state on the levers.  That being said, it also makes it possible to read the state of the offset and based on the value, an output line can be written in the MCP_CONF digital output file to illuminate the corresponding overhead annunciators. (note: this is not a standard MCP_CONF assignment.  You have to write the lines in the DigitalIn.cfg file so they will operate based on the position of your switch)..
ENG. & SPAR VALVE ANNUNCIATORS (OUTPUT) Two of the Digital Outputs have been assigned to Eng 1 and Eng 2 Fuel Valve OPEN.  Again, this is not a standard MCP_CONF assignment, you have to write the lines in the DigitalOut.cfg file.     RESULT, when the Idle/Cutoff Lever for either engine is moved to the Cutoff Position, the Engine and Spar Valve Closed Annunciators for the corresponding Engine Illuminate on my Hardware Overhead.
GEAR LEVER - (Input) My Gear Lever is connected to the Board and one of the Digital Inputs is assigned to Landing Gear.  There is a microswitch on the lever which is closed when it is moved to the Gear Down Position which in turn requests the MCPEX board to switch the offset and lower the Landing Gear.
GEAR LIGHTS - (OUTPUT)  Three of the Digital Outputs operate the Gear Down Annunciators on the Rear Overhead Panel. Result when the Landing Gear is down, the 3 Green Annunciators are Illuminated on the Rear Overhead (The Main Panel Lights are driven from the MIP737 Board).

LOWER LIGHTING PANEL (Overhead)
All the switches on the Lower Lighting Panel are connected to the MCPEX board.  The MCP_CONF (as standard) allows you distinct ON/OFF control of all the lighting on the PMDG.  It even turns the Wing Lights on the PMDG on and off.   LANDING LIGHTS - TAXI LIGHTS - LOGO LIGHT - POSITION (NAV) LIGHTS - STROBE - ANTI-COLLISON (Beacon) and WING LIGHTS are all controlled from the board.
STARTER SWITCHES
Two Rotary Switches have been connected to Inputs on the board. These are assigned to send keys (in my case F11 for eng 1 and F12 for eng 2) which FSUIPC sees and invokes the FSUIPC Mouse Macro for the Overhead Starter Switches (no they don't auto shut off, i'm not that rich).  Now remember the fuel valves.  Theses have to be opened in the Start Proceedure otherwise it's a non-starter (so to speak).  I've bridged the GRD and FLT pins on the switch so we can invoke an In-Flight Start if we have to.

MORE TO COME (No Time, Got to Go Service the Lawnmower :o)

MCPEX Manual

CREDITS
Pete DOWSON for teaching me how to Manipulate the Offsets in FSUIPC

PAOLO at CPFlight for teaching me how to write the lines in the Digital In and Out .cfg files.