I have no knowledge of MT Powerdrums, so I am not informed on its capabilities or limitations.
But one workaround if it isn't capable of multi outputs is to edit the midi track into multiple tracks, then render the results to audio once satisfied.
Duplicate the midi track as many times as desired, then delete everything but kick in the first one, snare in the second one, hats in the third one, etc until you have the desired tracks. Then render to individual audio tracks.
Perhaps something in this is useful as well?- (old and based on MX7)http://blog.acoustica.com/off-beaten-path/