Joint Stretching in an animation

Hi. Im trying to make some custom animations for a large mech avatar. My question is this though. When you export a BVH file from Maya, lets say, It seems to only care about the rotation values and not the translation values. Specifically i need to stretch out the legs. I need more distance between the upper leg, knee and foot.

Normally I would say thats an obvious "I'm out of luck" thing, However, Ive come across many animations in world that clearly use translational data and not just rotational. (Neck extend, etc)

I was wondering if anyone here knew how these were accomplished.

the word you'll want to search for on the forums is 'deformer' and it's accomplished by manually editing the bvh file before you upload to add the translations.

I've seen at least 2 good uses of this technique for av's but they were both people I didn't really know or have time to talk to