weltertm,
There is a trick. It involves wrapping a rope around the window rubber, putting the glass and rubber up to the hole, and while a helper holds and pushes the glass, you slowly pull the rope out.
This action lifts the lip of the rubber seal over the lip of the opening and presto, the whole thing slowly goes in. This is accompanied with a spray bottle full of soapy water applied liberally.
I did this once on a VW windshield and it worked great. Isn't the rubber on your window a two piece affair. The large piece that captures the window in the frame and a smaller wedge or 'lock' piece that expands the large one and locks it in the opening.
With the two piece rubber, you should be able to work it all in with plastic tools and soapy water. Then do the same with the lock piece...maybe not huh!
Stuart