I now have some motion on biped in 3dsmax, but it seems to be playing back very slowly. Is there a way to fix this before getting into 3dsmax? Changing the speed of a biped is not as easy as scaling out a few keyframes.

There are no time-editing controls built in iPi Mocap Studio.
If you see that the animation exported from Mocap Studio play a bit more slowly in 3ds Max than in Mocap Studio, then you probably should adjust the frame rate of 3ds Max project to match the animation frame rate before importing the animation. You can also adjust the frame rate of BVH file using bvhacker.