Just wanted to add to this. I may be repeating a couple things in here.....but my take either way..
1. All you need from the retrofit kit is the wiring. All the extra little pieces are just in case you break one of the pieces that are already there...or if you just want to replace them for the hell of it. The piece that is used on the mirror itself is hard not to break so you will probably have to use the new one in the kit.
2. You're just running the wires from the 20 pin middle/black connector in the upper/front console to the 10 pin connector in the mirror. I know this is something that should be common sense and easily figured out in the first place. But no DIY actually says this at the beginning. If I would have known that in the 1st place, I would have been able to do this MUCH faster. I spent an hour just staring at diagrams and trying to read through so much until I finally realized that. You have to cut the rubber piece off the retrofit wiring and then look at the diagram (best shown on the link below) and plug them in, then put everything back.
3. Make sure when you slide the gray 20 pin connector in the console back in..you use the arrow on it to slide it in the right way. I did it wrong the first time. Stupid I know...but just glancing at it, you CAN put it in wrong.
4. To get the console open, go in from the windshield side. I knew this from doing my LED interior kit. The clips are damn near impossible to do from the rear.
5. I cracked my windshield trying to put the homelink mirror on. So be VERY careful doing this. Hopefully your's won't be so damn difficult.
Best diagram for the wiring...