I just replaced the TCU in my 2004 X5 (06/2004 built) with another TCU with part# 84 11 6 946 993 (1st generation with 12/12/2004 build date) and bluetooth started working right away. I did not have to visit the dealer for any kind of coding. I do remember reading somewhere that lot of the late model 2004s were shipped with everything coded, they just did not have the bluetooth in the TCU functional.

I learned a lot about my new (for me) 2004 X5 reading these forums. Thanks for all the folks who added all the information on this site.