For future reference and endeavors:
The mirror doesn't need to come from an Infiniti or even Nissan vehicle. There's a company called Gentex that makes these mirrors and they're used in pretty much every car out there. I used the same mirror that leeQX4 used, but got mine off eBay for about $20 and was from a Chevy Blazer. Go to eBay and just search for "auto dimming mirror" and you'll see what I mean. The model number for this one in particular is GNTX-187 Part #015306
Wiring it up is pretty simple and the same for all of their mirrors that use the 7-pin connector. In the case of auto-dimming and those with compasses, it's a matter of providing power and (optionally) a positive lead to the backup lights (the compass is built in!!). Note: if you don't wire it to the backup lamps, you'll need to link to the ground wire or it won't work properly.
I pilfered this from a post at
http://www.the12volt.com/installbay/for ... p~TID~8560
GM wire harness color Function
PIN 1 PINK POWER +12 volts
PIN 2 BK CHASSIS, GND
PIN 3 LT GRN BACKUP LIGHTS
PIN 4 GY TO AUTO DIM OUTSIDE MIRROR
PIN 5 PINK TO AUTO DIM OUTSIDE MIRROR
PIN 6 DR GRN/WT TEMP PROBE
PIN 7 BK/WT TEMP PROBE
Auto-dimming with or without compass only uses the first 3 pins. 4 and 5 can be used for side dimming mirrors if you have them. The only requirement outside of that is a temp probe on 6 and 7 for those that have a thermometer built in. I can't speak to where those should go.
Gentex also makes a version with Homelink built in that I've seen on the Titans and Armadas (amongst others). They use a different connector, so different research will be needed.
I'm going to use the power from the compass built in to the overhead console for my mirror since it was right there, so we'll see how that fares.
Also, I cracked mine open (gentle but simple) and swapped the LED for an aqua 3mm from superbrightleds.com and used some hot glue in front of it to diffuse the light a bit.
Hope this helps and good luck!!