Just some pointers for you, dont overlook these couple of steps:
-After you loosen the window bolt (step 10), you then should push the window up all the way. This is especially important for those with window tint.....it will get scratched if you arent careful! Get some masking tape, and tape the window so it doesnt drop.
-Also, when you are buying the regulator, buy some butel tape. This is the adhesive that is used to put the foam vapor barrier on the door. If you dont, chances are you will get a water leak. And when you are reattaching the vapor barrier, work small areas back and forth with the fist of your hand. You will feel it getting warm from the friction, this will help seal it up.
Not a bad DIY write up at all. The front is very similar to this, with small differences.
YOU BOUGHT A BMW, IF YOU CANT AFFORD TO MAINTAIN IT............SELL IT.