To the best of my memory, the Korg Polysix accepts "S-trig" clock pulses to sync its arpeggiator (remember you can feed patterns into this, rather than a steady clock-stream, to trigger the arpeggiator as a riff, if you get my meaning).
And the VCF cutoff input accept +5V to -5V to sweep the filter.
But as others have already said, anything else you need to do manually with your fingers