Simple walk i MxS

Hi all! I am new here at the forum. I am an intermediate 3ds user, and I consider myself a beginner in MaxScript, allthough I am starting to get SOME hang of it ...
I can do the basics like doing operations on several objects at once, and I have made a car rig just like this (with terrain following and all):

Now I want to make something like this:

It doesn`t have to be that advanced. My goal is to make a couple of legs that follow the terrain, and a body. I planned to use sliders for speed and turn.
Could any of you point me in the right direction of how I should make the walk? How should the movement of the legs be controlled, and why?

I would be very grateful for any help :)