I just did this this weekend to my stripped 1M and it came out perfectly. Don't freak out (like I did) when you see the retrofit harness is just a bundle of 5 wires and some connectors -- follow the steps below, take your time and it will work perfectly. There are a few threads to follow through all of this and I will try to include the links (make sure you read through everything once before you start -- it really helped me be ready):
1. You need the retrofit harness: P/N 61120434330 (this has the wires A2-A5 in the pdf in step 3 as well as the brown ground)
2. Follow these directions:
http://www.e90post.com/forums/showthread.php?t=450516
3. This link (p. 11 on) tells you where to tap into the overhead console wiring:
http://www.keepandshare.com/doc/4229...m-1-3-meg?da=y
4. I found this picture (from e90 post) helpful in putting the wires in the mirror plug (14292; I don't think the stripped 1M has the wires for pins 8 and 9 on this diagram):
http://www.e90post.com/forums/attach...1&d=1308780520
5. Plug in, turn on and go! (You may need to start and stop the car a couple of times to get everything working)
Recap (from another post that I lost the link to):
1. Remove the old mirror and the switch unit.
2. Feed the wires of the new cable through the hole.
3. Plug the wires into X14292.
4. Plug all but the brown wire into X14288 (unplug it from the switch unit and disassemble it first).
5. Take the wire knife connector, feed an existing ground wire and the new ground wire through it, close the connector (I used a T-splice from Radioshack).
7. Install the new mirror, connect X14292 to it.
8. Replace the switch unit and plastic mirror trim.