Removing the door card shouldnt be too hard at all! Just some screws along the bottom, screwed in handle, then just pull away from clips and sealant!
However, swapping the electric motor would be one hell of a bastid job!!
I just spent saturday afternoon salvageing a leccy window switch and motor from a scrapped RT - and when id finished the door looked in a bad way!
There are only 3 bolts holding the motor in place, and 2 bolts holding the accompanying runner tubing in place - the problem is getting these out/and the new ones in - without mangling the parts or the door!!...Which is near on impossible!
It seriously may be easier getting a new door and attaching that instead!!