CAT can import motion from BIP (character studio Biped)files onto CATRigs. This is not the same as importing the original BIP file. You are not loading in the original keyframes.
There are no settings for BIP file import. Once you select the BIP file, the Capture Animation dialog opens right away.
The height of the biped, for scaling purposes. This defaults to the last value used; in general, set it as close as possible to the original biped height.
When on, automatically captures the animation, overlaying the new bones onto the CATRig. When off, imports the animation onto a new biped object without affecting the CATRig.
Click to pick a CAM mapping file if you have already created one.