I don't know of any way to use the BMW OE bluetooth to transfer music. Sorry. I do use an Ipod in the X3, but I connect through the AUX input ...

If you have an AUX input (normally in the rear ashtray at back of centre console) and a 'Mode' button on your radio head unit then you can plug the Ipod in that with an 3.5mm aux lead.
Press the mode button until 'AUX' shows on the radio display and if your Ipod is playing you will hear it through the sound system. You will have to chose tracks or playlists you want directly on the Ipod. You have no automatic (car) control over the Ipod and it doesnt integrate with your display or steering wheel controls. Sound is very good though (I've used this way myself on our 2007 X3).

If you haven't got an AUX input and want to fit it - or, if you want an integrated unit (Eg Ice Link Plus, Denison Gateway etc which can also charge the Ipod and depending on the unit they can integrate with steering wheel controls and radio display) take look at the 'Stereo Tips and Tricks' (point 5 and 6) here: Xoutpost.com - x3tips.htm. This will give you an idea of whats involved.