I completed a Cruise Control with Brake retrofit in my M235i yesterday afternoon.
For anyone who's interested to know, I've written a full How-To guide in my progress thread, here -
http://www.2addicts.com/forums/showp...0&postcount=20
I now have fully working Cruise Control with Brake function in my car, working perfectly! Installation was maximum 2 hours.
If anyone has any questions, just let me know.