Piece of cake. Clean them well. If they have a 'glossy' topsheet you may also want to hit them with a very light sanding. Tape off any parts you want to protect. Spray away!
I can't find any better pics, but here's a pair of K2 Public Enemy's that I painted flat black. I hated the graphic on them and was simply going for cover-up. So I didn't care about protective overlayers or precision. More going for the blacked-out beater-car look. It held u[ OK, but scratched over time. Which was OK too. If you want something more durable do a few layers, plus a few layers of top coat.
(The original point of this pic was the moose tracks, not the skis....)