I heard it used on E! in 1998 on a show having to do with skiing in the Rockies. Perhaps it does have roots to the existing definition listed here at urbandictionary, but extreme skiers have been using the term for years in reference to hucking or skiing off a particularly dangerous cliff or ski area. It's not limited to skiing but does seem to be popular on the West Coast.
"My perception of 'extreme' equals someone hucking themselves off a cliff on a bike, skis, snowboard, whatever."