Guessing your friend's using artificial turf on his summer set up? You'll want to use a very cold wax to protect your bases, something like Swix CH3 Powder or Toko Cold Powder, then iron in a Swix CH4. It's also a good idea to see if you can find a graphite wax eg. Swix LFG4, although they are a little harder to come across. Furniture polish will then help you slide faster. But to be completely honest, you'll wreck your skis if you're using them on a summer set up, if possible just use an old pair of beater skis.