If you do it the way alot of people do it includeing myself, its a spray called night shades that you would have to sand off i would guess. If you want to shade some to swap out i would just get a spare set.
Don't paint them! If you think that you might want to remove them later, use a film. You can peel it at any time. If you are concerned about installing them yourself, take them to a tint shop. They should do it for about $35 or so.