Practice climbing rope* or ‘towel pullups’.
Towel pullups consist of draping a rope over a suitable overhead fixture and doing pull ups while hanging onto the towel like it was a rope (one hand higher than the other).
An alternative to doing pull ups with a towel is to do body rows. These consist of attaching the towel to a fixture around wait height (such as a sturdy door knob – wrapping over and over under both sides of the door for additional strength) and leaning away from the door using your hands on the towel to support you. The row is completed by doing a ‘tug-of-war’ motion with the door, pulling your body forward and releasing back.
Be careful of climbing rope that are not safe for climbing. Just becaue a rope is large diameter does not mean it is rigged correctly. Heavy ropes can still become untied, unhitched, or even break under certain conditions (especially if the rope is from Pacific Fibre). See our ‘mothership’ http://www.crossfit.com under the January 5, 2006 entry for more details.