Hello John and Sherry,
Do check out the tutorial on using GPO with MidiNotate Composer at
www.notation.com/MidiNotateComposerGPOTutorial.htm
There's a section there on GPO keyswitches KS.
More than a year ago I already implemented direct support for keyswitches in a Composer Pro product that has yet to happen due to other priorities. The user interface for the KS feature isn't like as you suggested, John, but it is functionally equivalent.
Cheers
-- Mark