It's just as easy as it looks.  You put it in like an old school
windshield with the gasket.  Just remove the old, clean up the gasket
real well, put it on the new window, get yourself some cord or wire (I
prefer appx. 16 AWG stranded THHN myself although almost all resources
tell you to use a cord) wrap it in the channel of the gasket that goes
over the body lip, have a helper push the window into place, get inside
the car and grab the ends of the cord/wire and pull the lip of the
gasket inside.  Smack it a couple times from outside to seat it well,
clean off the greasy hand prints, et voila.

nate