My friend's sister has done a few for him. They're completely Sharpie I believe. The problem is sealing the artwork so it will hold up to all the abuse we put our skis through. She def did a sick job on these skis though.
IF you just want solid colors, I've seen alot of people who simply duct tape theirs. not exactly a proffesional look but hey if your skis are already beat up they can only get better..
I have. its very easy. remove bindings (ideally), Lightly sand, paint (spray paint), clear coat, reinstall bindings (epoxy screws in for no chance of pullout), and your done. pics in my profile