I don't know if MIDI connection or Serial connection work from within vsig, but here is what I do on G4 Mac: I programmed a custom Max/MSP patch to import and export vsig files from and to the Harmonizer. I use vsig inside Virtual PC to open, edit, and save the vsig files (text files).
It seems that with an Intel Mac, you may use the serial connection (check the archives of this forum or of the vsig one).
Communication works with the Harmonizer using either MIDI connection or Serial connection. I will definitely make these Max patches available. Is there a "share" space on this eventide forum or web site? I couldn't find any. There is no share space anymore on cycling74's web site either, otherwise, I would post the files there. To be continued… surely in 2010.