I can testify to the above plan by mikus. I got that drill out of Renzo Gracie's book and have been doing it at home. You'll feel like a dork at first because without your hands, your guard will get passed really fast during the drill. But you'll get the hang of it eventually, and it will really show in sparring when you can control someone with your lower body independently from my upper body. It has really helped my hip movement and the use of my legs.
And here is a term my instructor uses for people who get good at stuff like this:
MONKEY FEET (said with a Brazilian accent)
Chanting it will help you at the drill. I promise.