Terri, I pull the bottom rubber out with a very soft (New) 1/4 to 3/8 <span style="text-decoration: underline">(Pure)</span>nylon rope. I also place plastic sheeting, contractors grade, under the rubber as it's very slick and protects the paint.
Lay the rope behind the rubber with one end sticking out on top of the plastic sheeting. Holding the frame down, pull the rope out slowly and the rubber will go where it's supposed to. I hold the frame down using two small ratchet straps one end hooked to the lip behind the hood hinge above the firewall, over the top of the frame post and down to a door hinge. One on each side. As you put the frame in place you can gently tighten each strap to hold everything where you want it. It allows you to gently rock the frame back and forth to align the bolt holes and by tightening the straps, pull the frame down into place without loosing everything you have accomplished. After the windshield is bolted in, gently pull the plastic out from under the rubber. Works for me, but there a lot of different methods.
I agree with Doc when he said he'd rather replace three transmissions than one windshield.