I have about the same setup in my '06 330i. The 6FL upgrade threads don't cover iDrive and since the bluetooth is part of the iDrive, the MULF, MULF2, whatever don't seem to apply.
I ended up going with the Dension 500 for mine. Works by emulating a CDC and using the built-in MP3 ID3 system, it works pretty seamlessly with the iDrive and you get all the sub-menus for Artist, Title, etc (no artwork though). I ran a USB extension cable from the Dension's spot in the trunk up into my console and retrofitted the USB/AUX connector from the 6FL package so I have a jack in my console to plug in a thumb drive.