Each stepper driver I've disassembled (okay, all three of them) have had a cheap, slow opto-isolator input for the enable line, with a series resistor around 270R that's set up by default for 5V switching. So, yeah, as Andy says, apply +5V/0V to the EN+/EN- inputs to disable the stepper driver (/axis).

As both Neale and Andy say, though, unusual and specific wiring choice.

Also, as Andy says, those switches incorporate a neon indicator which won't work at these low voltages, rather 220VAC.