I haven't put my arms back on my E body yet but what I have done on other cars is install the whole set up but leave the actual arms off until the car is assembled. Then once the wiring and switch are in place, switch it on and off a few times to make sure everything is working the way you expect it to work. When it's in the off position, it should stop at the position where the arms are normally down. Then I put the arms on last.
If there is something unique about e bodies, hopefully someone chimes in and gives better advice.