Yeah I do this at my shop a lot, like SlushboxTeggy said using candy is the best way. The concept of using tint would work but would not be very durable, would scratch very easy. Depending on how much your looking to tint you wouldn't need very much candy, some automotive paint stores might even give some samples to play with. If it was me this is what i would do, take what ever you want tinted and sand it with 500 or 600 grit wetsand paper then take it to a paint and body shop and ask them to spray some red candy over it but ask them to mix the candy with some clear, candy is usually mixed 2 parts candy to 1 part reducer to 1 part hardener but you want them to mix the candy with clear so the mixture would be 1 part candy 1 part clear to 1 part reducer to 1 part hardener, you'll have a nice durable finish, you can even ask them to spray another coat of just clear by itself for more durability. Keep in mind with candy paints the more coats you apply the darker it gets. Sorry about the long post but just wanted to make sure you had all the info you were asking for, hope this helps. Oh and the reason i said sand whatever your wanting tinted first before taking it to a paint and body shop is because it will be way cheaper if you do the sanding, you might only get charged 75 to 100 bucks for them to just spray it.