Or if you get short screws like I was able to buy from my LBS, you can just screw into the knobbies and not have to worry about covering anything in duct tape.

Anyway, I seriously looked into making tire chains for a while, but eventually concluded that it would not yield the best results for riding on the streets, and would add a lot of rolling resistance. So, I decided to go with studded tires instead. However, I did find a couple of sites that may interest you concerning making chaings:

http://www.mtnbikeriders.com/2007/02...y-tire-chains/

http://web.archive.org/web/200605121...ne/chains.html