Stole this from some one here I believe. Not responsible for content...

1.Always start with fresh parts. i opted for OEM but that's cuz i'm doing this the right way.
2. Working that nice new weatherstrip on around the nice new windshield make sure the seam where the ends join is placed at the bottom center of the glass.
3. Just keep wiggling the weatherstip on.
It's a total pain in the hands. if your fingers don't hurt, you did something wrong...
4. Ok, so the weatherstrip is on the glass. now work your way around it again and seat it properly
5. Work the cord into the weatherstriping leaving a loop out so thet you can grab it from the inside once the glass is in place on the frame. note that i've started at the seam that will be on the bottom of the frame.
6. Once the glass is laying in place on the frame with the cord on the inside, grab the cord at the loop and start to pull up and to the side so that it pulls the weatherstrip from outside the frame to the inside as the bead flips up over the lip of the windhield frame. then just work your way around. i paused evey few inches to push the weatherstrip down to seat it on the frame, and the glass to seat it completely in the weatherstriping.
7. You can see the way the weatherstrip is half on/half off on the bottom of the frame. that's where i started.
8. This is where you really put some effort in. wear a glove or you'll rip your pulling hand up. go slow so you don't pop the glass at the corner.
9. That's it. Glass is in place. I worked my way around the inside fully seating the weatherstrip all around and then moved around the outside shimmying it into final position. Whole task took around an hour.