Just you've got to be a bit canny about making sure that the first time use disclaimers are used and stuff, check http://www.mamedev.org/legal.html just to make sure - I think you're OK.
If you look at the links for MAME Hooker, you might be able to see how to get an interface to MAME's outputs that you can play with, I'm not really too sure about how it works myself, suffice it to say that MAME sends on off signals for lamps and leds. The main issue we would have is that MAME smooths the lamps out, so you don't get the dimming effects that your stuff is capable of. Can I suggest you let me contact some MAME peeps about this - I mean, it used to be done for Visual Pinball (called, funnily enough, Visual PinMAME), but I think they did some sort of visual basic DLL compile that didn't make a lot of sense to me.
Actually, just written a belt reel visual method for MAME, but deliberately held off from posting about it yesterday, as me waking up would have been to much like a joke for April 1st.
I can give you the info for lamp dimming if you want to add it to the drivers. Its fairly simple to do.
