If you select all of the animation keys in the sequencer tray, then hold down the Option (Mac) or Alt (PC) key as you drag, the keys will be duplicated and keep their original time offest from each other. If you then drop these points at the right distance from the originals, you will have continued the walk cycle for a 2nd iteration. Do this agaqin, with all of the keyframes, and you will have 4 cycles. Repeat as desired, and you will exponentially increase the length of your cycle. I've used this to continue an animtion cycle, but I found that it still needed some editing, especially the tweeners. If you have any tweeners set other then your default, you'll have to go back in and reset them to what they need to be. (Or, at least in C1.2 it did. I haven't done it in C2 yet. Maybe they fixed this.) Hope this helps! :>