See http://rebrickable.com/mocs/isogawa/fleet-footed-insect?utm_source=newmoc&utm_medium=email&utm_campaign=newmocthresh

We didnt have the correct parts for the back legs so improvised. The 2 most useful bits though are these as they're rubber and would grip the floor, and we dont have those either. Ours did 'walk' but not nearly as well as the official one.