Hi Ed;
I think that the HW manual says quite a bit about SysEx messages starting at page 221.
HW provides a lot of options for message types as inputs to virtual stops but only three options for output. The "Auto MIDI output (match to primary input settings)" looks interesting for your project. There's three SysEx input options available, Johannus 9/11-byte sys-ex , Viscount 6-byte constant sys-ex format and Generic MIDI sys-ex constant messages.Of the three, I think the Viscount and Generic options may have promise seeing that the console in question is generating simple 6 byte SysEx messages.
Try setting up a virtual stop with these options and see what HW spits back and what the console does with it. If it explodes.....well.....it is New Years and fireworks are appropriate.
I don't hold high hopes for the Viscount approach to actually work because bytes 2-4 will likely not be the same as what Viscount is doing and HW may not know what to do with it, but it should be easy to try. On the other hand, the Generic option could be just what you are looking for.
Another approach is to use MIDI-Ox to send a SysEx message to the console and figure out what values do what - no need to involve HW for that. Once you know the map of the console I'm sure John Kinkennon can come up with a custom microcontroller that would translate HW output into what the console requires.