By the switch button, are you referring to the DZ-2502 Push Button Remote? If yes. you may need to use the DZ 1002 push buttons instead. This is one you will have to run by Dennis Zander at Z-stuff drzander@aol.com .
The Z-Stuff instructions (accessed here, http://z-stuff.net/instructions.html) mention the DZ 1002 with the AIU and DZ 2500.
My DZ1002s (the DZ 1000 Switch machine push buttons) are wired using the AIUs as terminal blocks so that my left and right control wires go in and out of the AIU taps.