before you go and waste your time applying tint or paying someone to do it, check into getting laminated glass - like ben was saying - that has the tint in between two panels of glass. the safety glass that has been mandated on all cars since the '70s has a thin plastic membrane in between the two panels of glass, so that if the window breaks it doesn't shatter all over the place. they just make the plastic membrane a little darker than normal, and you can claim it was done at the factory. the best test if a razor blade (carry one!) that you pass over both sides of the glass to prove that you didn't apply tint to the windows.
i do not know how legal it would be, but a cop would have a hard time writing you a ticket for something you can't remove. and, as far as inspections go, if they fail you then just swap in the original glass (yes, you're going to need it at some point so keep it safe) to pass inspection and put the tinted ones back in when you get home with your new inspection sticker...
of course, if you do decide to follow my advice (which i have already stated that i don't know if it'd be legal or not) you're on your own. don't try to drag me into court to help explain to the judge what you did...
