For the wiring, PM Crash on PBB - he's a GM tech and can probably rattle this off the top of his head...

For the ECU, I mounted mine on the bottom of the glove-box in it's factory black plastic cover.  I mounted the diagnostic port just to the right of it below the speaker.  I used one of the heater motor mounts and black zip-ties to hold the ECU in place.  You can see the diagnostic port to the right of the interior cage here.  The black mass below it and to the left of the downbar is the ECU cover.



No one would really even know they are there if I didn't tell them.  Out of the way, yet accessible.