OrganAssist includes a number of Hauptwerk organs and you could look at the MIDI configuration for each by opening Edit Organ Layout for the different instruments. You could use this data or, even quicker, you can import MIDI files and then export them for playback on your organ, once you have set up a configuration (if it is not already included or on the download page of my website -
http://www.organassist.com).
[Edit] Since the MIDI configuration does not show the final result (as it is calculated before sending), the best way to see the MIDI data is to leave the PC MIDI Setup window open and operate the stops on the screen. You can then see the MIDI messages as they are generated for each stop.