Very easy to do. I find it easiest using a few flat teaspoon handles. Work your way around the edge, gently manoeuvring the the seal behind the glass. When getting to about half way i usually open the boot all the way to make sure it cant fall anywhere.
Easiest way is to smash with a sledge hammer then super glue on refitting!
Seicento has a bonded rear glass.
on the tailgate ???? not on my mk1 sx it hasnt
Lee
You can get away with using Tigerseal (etc) on rear windows, but there are special adhesives available with something like half the curing time. (Important in these lowish temperatures.) Talk to your motor factor.
Alternatively, the mobile screen fitters round here do it for 30 quid (most scrappies have a contact).