Thanks for all the tips guys- I managed to get the driver side windlace in by myself...pulling and pushing and guiding, and now my hands are killing me...! I used pliers to pull down on the end of it (the end I was going to trim off). Hope these things outlive me, because I never want to do it again- I'd rather do four windshields than another windlace!
It really would go faster with four hands, but I've only got two right now. You guys were right about small imperfections in the channel holding things up. When I do the passenger side, I'm going to invest some serious time inspecting and prepping the channel before I start.