SEM Vinyl Dye (Can be purchased online for approx. $10 per can, also called SEM Color coat, don't be confused by this, it IS the vinyl dye. People here have used VHT dye as well and seemed to have great success with it, though I have never actually used it, you can give it a shot.)
Not trying to be an ass, but the SEM color coat is an interior paint, not a dye, it says it right on the back of the can. Anyway, I am in the process of painting some interior parts and am impressed with the quality, just wondering how it looks in the long run? BTW, it looks great!