Riding up will probably impossible or be tough as hell, and it would probably become a hike-a-bike ride. The ride down would fun though. To rig you tires, Take sheet metal screws and screw them from the inside out through the knobs, just make sure you have plenty of clearance or you will chew your frame up. You can line your tire with a slick tire with the bead removed or just use a lot of duct tape, but definitely line them or you will definitely be walking your bike. I have done a couple of races on snow at ski resorts, and it is hard riding, it is more sliding than anything, but a lot of fun.