Have you tried the standard Pairing functions? I'm not sure if BMW coded their BT integration for only specific phones and I know that getting the info into the MID display might be proprietary, but hopefully you can get the hands-free BT function going.
I don't have BT yet in my E39, but might add it later.
To answer your question, you might want to post it on the following links depending on if you have an E39 or E60. There's a gentleman by the name of Johnathan Spira who knows quite a bit about BT in the E39 BMW's.
http://bimmer.roadfly.org/bmw/forums/e39/
http://bimmer.roadfly.org/bmw/forums/e60/
