From the other thread:

"removing the winsheild without breaking it is a serious chore. You need some piano wire or something thin and really strong which you feed through a point in the glue and then (with a partner) slowly pull it along the whole windshield. Of course, before that you have to take off all the trim, which isn't that simple either, and you have to get a clip kit if your car is older than a '90. What I did on my car a while back when I had these same rust holes was to just pull up (very carefully) the sections of trim where the rust was and then grind them down, paint them with por-15, and then I filled them with silicone I think or something of the like that was water tight. Then I covered it with body filler and painted, and it hasn't leaked since in about a year. I would try that first, before going to the hassle of taking out the whole windshield. Well, best of luck!
Nate Gundy"

That's pretty much it. Remove the trim, take a thin wire (like piano wire) and thread it through, with a friend on the other side move it all around the windshield, pop it out (from the inside, with your feet), clean the gunk (glue), put down new glue, put in the new windshield and gently press down all around to make a good seal, replace the trim, and cross your fingers that the glue was solid and the new windshield doesn't leak. I've only done this once, many moons ago on my then car, a '79 Plymouth Horizon. The friend "helping" me actually had a parttime job at a glass shop installing car windshields (we were students). So I guess I can't say that I actually replaced it, but I was there the whole time as he did it. The used windshield was from a junkyard, the interesting thing there was that I got two prices: One for if I removed it myself, cash in advance and if I broke it, too bad, the other price for if they took it out, guaranteed to be intact. I didn't break it when I took it out (with a different friend).