I'm sure David has done a lot more of this stuff than me and I'd like to hear what he has in his bag of tricks for this task as well . . . I've got a "new" (used, but new to me and in good condition) windshield for Homer the Super Bus.  I've installed one Bay Window Bus windshield without breaking it, but I think that was as much beginner's luck as anything!   :lol:  I'd like to hear David's tricks before I try it again.  Here's the few tricks I have used with some success:

1  Use a heavy weed-eater cord instead of spun or twisted string or roap.  It slides over the rubber better without biting into it as much.

2  K-Y Jelly for lubrication.  Don't laugh, IT WORKS!  Superior lubrication properties and doesn't hurt the rubber or paint.  But, it doesn't protect against STD's according to the lable.   :lol:

3  Don't try to install it unless the rubber is warm.

4  Wrap the weed-eater cord twice . . . if you don't get it all the way in the first time around, you get a second shot.

5  Don't let your helper apply any more than a very slight amount of pressure, and only at the very edge of the glass where the string is pulling the rubber across the lip.

6.  Don't get in a hurry.  If you get frustrated, walk away before you break the glass and try it again later.

Zen got it pretty close.  I used about a 1/8 inch nylon cord with a piece of copper tubing to feed it into the channel on the seal along with some pure silicon paste.  I never tore up the rubber with that cord.  As far as installing goes, Its pretty much as Zen said.
        The only other trick I know is knowing when to drive to Grants when you are installing a curved windscreen in a Super-B or a bay window bus.Its money well spent and you don't  drink/sweat as much. They can put that glass in faster than it took me write this post :lol:  :lol: