I had to do it in my 94 f-150 after some other people decided they wanted my truck more than I did.
The guy at the junk yard and I each grabed a flat head screwdriver and very very very carefully pryed the top portion out a bit, then the bottom portion a bit, then the top... Also, it was a warm day when we did this, like 80 degrees and it was in direct sun light.
To put it in, we managed to save the rubber seal and I just lubed it up real good with some dawn dish soap. and slid it in. It took quite a bit of effort and lots of soap and water, but it is in now and works perfectly.