Brad, yes you can paint them. They make a plastic paint...I think it allows more flex than regular. When the shop where I live painted mine I thought it was something they added to the paint.
Edit...and here is a rattle can made for plastic Rust-Oleum Black Automotive 248649 12-Ounce Paint for Plastic Spray, Gloss, 11 Ounce (Pack of 1), 12 Ounce - - Amazon.com