How to get the screen out gently (sledge hammer... very messy... much fun)
Get a plastic scraper outa the kitchen, outside the car, lift the seal, slide the handle end of the scraper under the seal, go around the whole seal, spraying the hole with WD40. The idea is to free the seal from the body work with out damaging the paint.
Inside the car, repeat if possible, but you must go around the whole seal and lift it so it is free of the trim.
Get a mate, work from the top cornors, pulling the seal back with your fingers, pushing the window out with your thumbs, working towards each other to the top middle of the screen, then keeping a firm, but gentle pressure on the top of the screen, start wroking down the sides in the same way, and volia, an intact screen and seal.
Fitting:
Lube her up right nice, no really
Washing up liquid or red rubber greese.
Fit the seal to the windscreen
Get some tough, smooth string, about 3mm is about max thickness.
put the string in the groove that the body work is goint to sit into of the seal, start at the top right cornor, working across the top edge, around the window, past the begining of the string and back to the top left.
with a mate,
lay the screen into the 'hole', trying to slide the sceen up and as much into position as possible.
get your mate to lean on the screen at the top cornor of your choice and pull the string end gently in the direction of the string, working around the screen together, him pushing, you pulling the string at the same rate. You will see the seal get dragged onto your side of the frame. When you get to the last bit, it gets a bit tight, but be stong and gentle and you'll be ok, once in, go around the outside and give it a shove to try and settle it.
Cheers
kraM