Wow, giant flurry of responses. Yeah, it would be a vehicle, rather like the skis, although it would
A. Not have the skis (Durr)
B. Not have anything to do with the skis
C. Not slide, just walk. This should be possible with a vehicle, although I am not sure exactly how. I think it might end up being rather hacky.
D. Fall over when the angle was too much, and sustain 5-15 damage
E. Be able to jump when touching ANY surface, but adding velocity in the direction that is at a right angle to the surface.
F. It would run and jump higher.
G. It would play the running animation, just the normal one, but I am not sure how exactly to do that. Possibly there's something in vehicle scripts that stops it from playing, but I am unsure.
H. It would probably be unable to mount vehicles unless it got rid of the player vehicle.