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A bit of a hack but we noticed a midi-to mini-jack converter (like the ones which are provided with the Beatstep Pro, Electribe's and lots of other hardware which use mini-jack MIDI) can be used to get a pulse into a sync trigger port.
We used this to experiment with the RK-002 and bring a MIDI Clock to Sync firmware which is also able to halve, double or... the relation between the midi and sync clock, allowing you to synchronise tempo on a different level.
Still figuring out how to rename the proper sync divider-number to a readable format (Did we already mention it was beta?)