D shifts the row
E+F addresses column D
and that's all.
Use the little knob below the paper tower to turn the thing on and off.
One tube surely goes to the additional long pin (that pushes the diecase draw rod into the upper socket rather than lower) in the front pin block.
There's an air valve actuated by one of the cam levers (springbox one if I recall correctly) that delays the air flow to the additional pin, so that the diecase is shifted in a proper phase of the machine cycle.
Signals D, E, F from the paper tower, output to D pin and the air mains go to that block too. I don't know how your machine does it (it's slightly different than ours when it comes to the location of the unit shift switch), but it looks like the quadding and centering attachment pass through that block on ours. That's probably just a passthrough with no signal split, though. Only the air mains seems to be split.