I need to install (nearly) new seals for the rear pop-out windows on a 123GT. I've been trying with the same approach I'd use on a windshield -- open the channel with a length of cord, and then pull them onto the car (except that they pull outwards from the inside). I can almost do it if I start at the rear corner and work going forwards, but I can't get the front few inches to pop into place. I've had no luck at all starting from a different point.

Does anyone know the magic trick do doing these? They are rare and spendy, and I sure don't want to pull to hard and tear the rubber.