Turns out I was looking up the wrong tree, after all.
While reading this, I came across the distinction between Boot Protocol and Report Protocol. Activating Boot Protocol with “left fn + left shift + esc” makes the M01 work perfectly with the Wombat (well, modulo a few key assignments, which I guess will be best dealt with a custom key map on the Mac side).
How hard would it be to have the M01 default to Boot Mode (“rebuild the firmware”, I suspect), and what are its restrictions in general use?