I did something similar but with old parts I had... I dual modded a 360 fight pad with a chimp (ps3 + imp for switching boards). Had them wired to the respective connectors of the cabinet so if I want JVS, I unplug the two connectors and connect them straight to the back plate, if I want PC/360, I unplug and put them back in
The whole I used to pass the USB cable through was the last connector
if you're using the stock monitor, HDMI won't ass through audio as it is a DVI monitor, you will need some sort of HDMI audio extractor to output the audio into the Audio In on the STD connect PCB.
For PC Audio, I have a 3.5mm out from the pc to a stereo RCA that goes into the STD Connect PCB