I was wondering if you can tint the softtop rear 'glass'?
(I know its not glass, don't know what it is called..)

Does it require a special film or a normal one, or it will just wont work..?

 

what year is your boxster?? i have an 08 and the rear window is tinted, they didn't need to use any sort of special film its just a pia to maneuver behind the seats in order to get to the glass.

 

....ditto. Here in Florida they are pretty good at it and it seemed to be a normal day for the installer with no complaints from him about the job

 

I think they are referring to the early 986 which had a vinyl rear window... you cannot use normal tint film on it, the only way to darken it is to replace the vinyl window with a darker one which they do make... an upholstery shop can do this for you but it is not cheap.