Not sure, but here's a few things that may help. There might be different solutions depending on if the alarm is factory BMW or aftermarket.
http://forums.bimmerforums.com/forum...d.php?t=929318 http://forums.bimmerforums.com/forum...d.php?t=787523 Will the car start with the alarm going off? If so, maybe you'll have to find the alarm speaker and disconnect it.