Anything is possible. Though doing this is pretty expensive. The OEM lamps are only available as a complete headlight assembly. You can get the assembly without adaptive headlights for $680 each. Then the cost of labor and re-coding.
EDIT: I forgot about the auto-leveling... That would be required for the xenons as well, if your halogens don't already have that capability.
Look here:
http://e84.xbimmers.com/forums/showthread.php?t=556512