The AIU is really a very simple device. It is not aware of what you have it connected to. The board supplies +5v on one side and a ground on the other. It watches for the individual channels to be grounded. You can even just ground them by shorting them with a piece of wire. Any type of sensor, set of contacts, or relay can be used to close and trigger an AIU channel. In the simplest terms it is a 5V DC data line with a standard (+/-) connection. The circuit is normally open. When the circuit is closed / completed, the channel is considered active.
All you need to do is pick a set of two contacts that will change (open / closed) when the switch is open or thrown.
You have several choices
Use pins (2 and 4) or pins (2 and 3)
That’s only on one side
You still have two on the other side!
Use pins (5 and 6) or (5 and 7)
In each case it does not matter which pin gets connected to the AIU channel and which gets connected to AIU ground.
All that matters is that the circuit is completed / shorted. Or the circuit is open / not connected/