There has been lots of discussion in the Moab threads about sand.
Yes, the TW can do sand. Air down the rear tire and make sure there is little weight over the front, i.e. No front rack with stuff on it and no front tool/tube bag. Speed is your friend in sand. Get into second gear or higher as fast as you can and keep the power on and your weight over the rear wheel. Do not fight the bike, let the front end wander a bit.
These are my tracks at Sand Lake in Oregon. I was trying to take the shortest path from point A to B, but notice how I am all over the place. I let the front tire have a lot of freedom in the path it chooses. An ATV tire also helps on the back.