The Dyanimat Toolbox is MATLAB code that I wrote for simulating legged locomotion. I gave a presentation about it at a workshop on Bioemechanics and Neural Control at the Mathematical Biosciences Institute in Ohio in January 2008. You can grab a copy of my presentation here.
The Dyanimat Toolbox is currently undocumented and only one person on the planet knows how to use it (me). I find it easy to use. But I would. When I get time to do some basic documentation I'll make it available.