Look for a product called Carbona Stain Devils. It comes in different formulations depending on what you're trying to get out. (Found typically in grocery stores in laundry section.)
According to Carbona, the Stain Devil formulation #1, made for nail polish, glue, and gum, is appropriate for paint removal.
BUT....closely follow the directions. It isn't a prewash but instead a stain remover to be used before washing.
And it works darned well. Left an ink pen in a shirt. Washed a load of shirts and pants with it, it exploded and stained a lot of clothes. Noticed it when I was taking the laundry out of the dryer.
Nothing was budging the stains on several pairs of jeans and shirts. Used the Carbona recommended by them and used it as recommended.....amazingly, the ink---VERY set in by this time----slowly but surely came out of everything. You'd never know any stains were anywhere.
http://www.carbona.com/index.asp