The scaling would only be done at the 1st frame. Then, Poser's Figure would have the same proportions as the incoming BVH. If that is true, then perhaps the Poser Figure will move correctly (i.e. as intended by the original BVH). Thus,  no jerking or foot sliding.

I am not intending on changing the world here, I was just keen to watch some of these Carnegie data files within a Poser environment.

Otherwise, I agree with rokket, importing BHV data is generally not the best way to animate.