How to Jump Start from the starter?

A 1991 BWM doesn't have a key that can manually open the door lock? That's really strange. All the pictures I find of the 1991 5 series have a keyhole at both the drivers and passenger side door handle. As a matter of fact that's down right stupid engineering. In any case I would call someone like a locksmith or something to use a "slim-jim" or something similar as if you locked your keys (or in your case your nonexistant keys) in the car.You can also download a service manual for your car free at: http://luuk.xs4all.nl/bmwboeken/Bentley_BMW_5-Series_Service_Manual.pdf This may help you out a bit.

Get a floor jack and lift up the front of the car. Get under need and look for the starter it has a thick red cable coming from the battery, that is the positive and the body of the car is the negative. Use the jumper cables to get power to the doors and open them then open the hood and jump the car. Good luck.