Correct, that is the only part you will need besides your new mirror. I just did the same mod this weekend. You should be able to fit any mirror with auto-dim, compass, and home link, including the one from the newer LCI cars without the clown nose.
Read the whole DIY for additional tips for wiring install.
http://www.e90post.com/forums/showthread.php?t=450516
Install takes 30 mins.