OK, it looks like this is going to work. I've got a way to mount the empeg and I found a device that will allow the empeg to work as the source for the factory HU.

I'm now wondering how to get the other wires hooked up to the empeg. (power etc). I can't just buy an adapter from Crutchfeild because I'm not replacing the factory HU. Do I get power, accessory power and headlight sense from the dash or fusebox? Sorry, I've done 2 empeg installs, but never one like this.