digital egr valve info

OK, I'm still 'bench-racing" my high-mpg project, and now I'm looking for info on the digital egr valves that GM has been using for the last 15 years or so. I'm MegaSquirting, and I'm checking into software changes that will allow me to control a pulse width modulated egr with it, but I also have a friend who's brave enough to help me build a stand-alone control if I need it. But... I can't find a wiring diagram of the internals of ANY digital egr, much less the ubiquitous GM unit. I also have one from an '03 Acura, so that wiring diagram would be welcome as well. Can anybody help?