I screwed up, neep help

I just went through something like this with my 64 Dart. The trim you need installed first should be installed before the glass goes in. That trim gets screwed into place using the trim clips as the hardware. Those trim clips then hold the weatherstrip trim in place.
I needed two clips at the bottom and I was able to rivet them into place from the inside of the trunk. If I needed the others, I would have had to pull the rear glass. There is not enough room between the body and the rubber to run a screw in or out. Let alone the fact you would need four hands to hold trim, screw in a clip and hold back rubber all at the same time. Good luck and let us know if you find a way to do it without pulling the glass.