For each of the 569's rows you use a rotary switch to select one step, as soon as it is played the gate output will emit a gate signal at the according socket. And also each time you press the manual gate button.
The rotary switches have not one but four OFF positions, making it possible to turn off the individual gate very rapidly.
four gate outputs, one per row of the M569
5U module in Moog form factor, one unit wide