I personally use MAC Mineralize Skinfinish Natural to set my foundation, but if you're just trying to use up your Bare Minerals powder foundation, I don't see any harm in trying to find other uses for it.
You can try applying a very small amount of the powder very lightly with a large powder brush. (ETA: Since it is a powder foundation, you have to be careful not to use too much or it might get a little cakey.)