[mrnoble]

I can only think of two approaches that will work and meet the requirements of the rules (or at least their spirit, as I read them; QA will need to clarify some things on the 9th). Approach #1: a caterpillar, either outside or inside the corner. Approach #2: a human/ape approach, with at least two grasping and releasing appendages. You can't balance on two rungs, as you won't be able to touch three zones at a time.