[Zeke]

OK, the first thing to do is act quickly. That paint is made to dry fast and be hard as a stone as soon as possible. There are several solvents available to remove stuff like this. I'd start with rubbing alcohol and then use tar remover if the alcohol doesn't work (alcohol is for waterborne paint, the solvent in tar remover should dissovle fresh oil based paint). Be careful not to rub the gritty paint you are removing into the car's finish. go gently and use a lot of soft towels. You should be able to get everything at a local store.

There was a thread about old overspray last night. Some good info there. Test anything in the trunk first and don't even think about lacquer thinner, acetone or brake parts cleaner.