Gahh, my friend and I were eventually gonna do one of these together, and haven't gotten around to doing so yet. As long as multiplayer is allowed, I'll get on it and hopefully have a good replay for ya.
Yes. Use your legs, elbows, chest, head (my friends and I use anything that isn't between our forearms/wrists/elbows), and keep the hackysack in the air as long as you can.