One shot mode for the sequence playback. You'd need some sort of retrigger or any sequence in one shot mode would play once when play is pressed and not again until playback was stopped and started again.
I wonder if this could be done with an external clocking trigger or tweaking the external midi transport controls
You could do it like that I guess, but it would affect the entire unit, not just one sequencer. Some way of remotely triggering mute would be more successful.