Ya know, if I went the modding route instead of programming all it would take is a little breakout box that gives me a shared start button for two gameboys. Could probably rig it up with an actual crossfader (like with button contacts at each end) for maximum wankitude.
EDIT: Has anybody developed simple button breakout pads yet? Like a little membrane that sits between the button pad and the pcb and has two wires coming out of it that you can link to a button at some other location of your choice.
