Yeah, some people were building these a while ago (when vpinball/vpinmame first came out)
I was going (and haven't had time) build a control panel just for pinball games.. It would have an upsidedown box over my control panel. That box would have the buttons on it... but there would be 3 buttons pointing back (so they are inbetween the floating upsidedown box and the cabinet) that would be hooked up to the tilt buttons.
Never got around to doing it yet.