Quick update: I have added the PC (notice JEG'S logo), test monitor and keyboard (The actual monitor is a large 24" tube that is mounted in the cabinet already). The I-PAC works well as a pass-through but since the ground connections aren't hooked up on any of the inputs I have not yet tested the "wedge" functionality for buttons and joysticks.
The PC is a simple XP SP3 box with WinIPAC installed. I have not installed and configured MAME yet, but the WinIPAC software will allow me to test the controls and debug wiring.