Quote - is there any way to make a character follow a walk path?

This is off the top of my head without testing, but I think that it will work.

Create a pz2 file that locks every actor except BODY. Make another pz2 file that unlocks every actor.

Set up your walk path, then apply the lock pose to the figure. Run the figure through the walk designer. This should give you the motion for the BODY actor, without affection any other actors in the figure. Finally apply the unlock pose.

It should not matter if you do the above steps before or after applying the bvh.

Whilst I think this should work to make the figure follow the walk path, without changing the pose of any part other than BODY translations and rotations, unfortunately it probably won't give you what you want. Making the figure follow the walk path is not much use in itself, unless you can synchronise the motion of the BODY with the motion of the legs, or vice versa. I don't see any easy way to achieve that synchronisation.