Later build of 8/04 received the BT/assist. I think you have the assist only like mine (7/04 build). Post 3/04 build may be upgraded to the MY05 TCU BT/assist combo.

"In order to do this mod you will be replacing your Assist module with the
combo Assist and Bluetooth module - part # 84-11-6-946-993. The part
itself should likely run about $440, but you will also have to pay your dealer
to have the vehicle coded to make this work. Per SIB 84 13 04, the
vehicle must be recoded in order for it to function, which will likely run you
at least an hour labor. So you might as well have the dealer install the
module too."

Link to the thread: http://www.bimmerfest.com/forums/showthread.php?t=80391
The TSB is in http://bluetoothyourbmw.com/. #16 and #17 under
Installation and Retrofit Guides and Information

This should not require a pairing button from what I've been reading as it will not wire up correctly. It's also written in the SIB 84 13 04. Hope this helps you out. Keep us updated.

__________________
-Arjay