This is an older video for Snowboardaddiction.com. YouTube - SnowBoard Addiction How To Backside 360 Extreme!!
This is the newest one, not on 3s but spinning in general (both directions) YouTube - How to 360, 540 and 720 Frontside or Backside (regular riders) from Snowboard Addiction.
These are probably the most "by-the-book" way to go about learning a 360 or any spin.
Last edited by LouG; 12-28-2010 at 12:57 AM.