Please see this post from www.m3post.com
that discusses the alarm retrofit kit sold in Europe. Apparently BMW NA has no plans currently to sell this part, but hopefully this will change soon.
The kit contains the wiring harness and all parts required. For sedans and verts with premium package and comfort access this should be a moderately easy install, but coupes may require modification to the headliner (yikes!). Non comfort access cars will require a mod to the driver door locking system.
The part # is 65120399635
Price is ~$350.
The 335i I'm expecting to receive has Premium and Comfort access so I'm optimistic. I'm going to wait until I take delivery to make certain it has the mirror with LED.
Wondering is anyone has experience with this retrofit kit?