It it is the same system as the e34 electric seats then its not too bad to do once the seat is out ( e34 drivers is more work due to memory option ) .
Basically you loosen the two 8mm screws on each side where the cable goes into the motor and pull the cable out . I pull the cable out and remove the plastic piece inside as well .
I now heat the silver piece with a lighter , not too much , and pull it off with a pliers . Now I cut about a 8mm long piece of the sheath off , heat it up slightly and push the silver end piece on , insert the plastic guide and the cable .
Assemble and test . with the seat out i used a spare battery to test the passenger seat , drivers I had to do in place .
Good luck .