could this be triggered by some sort of drum triggers like alesis performance pad pro if you put some Midi-to-CV inbetween?
and if you did i take it you could swap some of the resistors so you had control over the length and pitch of those analogue drum sounds?
If you used a midi to trigger converter you could probably drive the CB55 with an Alesis pad, i don't think you'd get any meaningful velocity sensitivity out of it though.
I haven't worked any out any mods yet, but there should be a few possible i.e. replacing R33 with a pot for bass drum decay time etc