I have started a hardware project for the Thorsten's Space Shuttle, It is an I2C "Data Entry Keypad" non-illuminated, that communicates to a micro-controller that in turn will communicate to flightgear over serial/virtual com port. I am wiring this as though it was the AFT keypad (only one electrical connection per button contact as opposed to two connections per button on the C2 panel) They both work the same way just the communications channels are different on the actual shuttle.
This is essentially an 4x8 matrix keypad using tactile switches connected to an MCP23017 IC, The images below show the project before the appropriate capacitors, resistors, and wiring connections are completed. The keypad, for those of you that don't know, functions in a row, column fashion to determine which key is pressed. A micro controller must energize each row and column in a specific sequence to detect a capacitance change to determine which key is pressed. Common pitfalls of matrix keypads are an effect called "Ghosting" when multiple keys are pressed, there is a specific pattern of this ghosting and those key sequences can be ignored.
This is a prototype in the works