If i recall, you can remove the door panel. and then remove the foam cover, then place a towel, or shop rags in the bottom of the door to "catch" the window if it happens to slip down. (dont ask me how i know this!!)
now, you can access the power window motor, unbolt it, but be warned, it will probably fall down very quickly!,or it may just stay put!
either way, once the motor is removed, it will (should) move, you may have to slip the cable off the roller wheel and allow it to come down.
either way, youll end up having to remove the regulator track out of the window, and realign the wheels and wire again. once you get the window free, its a good idea to remove and replace the plastic clips on the window (they wear out and could cause problems by cracking and they are about the cheapest part youll ever get at a dealership!! I think the complimentary coffee is worth more than the parts!!)
ok, then put everything back together (but not the door panels) check the function of the window now, (dont disconnect the air bag or youll get a code!) I cant remember if they need to be "re initialized" or not, but test them out a few times, make sure all is well, then reassemble the doors,
good luck!

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2003 X5 3.0i (02/2003) sport package, Sapphire black metallic / Black Dakota Sport seats. compass mirror retrofit, trailer hitch retrofit, Prodigy P2 trailer brake controller installed, PDC retrofit, Lumbar support retrofit. heated rear seats retrofitted. Running boards retrofitted and subwoofer install in progress. 4.8is Brakes installed front and back. Bluetooth TCU installed, Rear Fog lights installed. Retrofitted reclining rear seat backs.