soldered and wired both y-axis limit switches in series NC between GND and the input pin. Got the Mach3 CNC software to recognize and work for both the X- and Y-direction for limit stopping and homing. The below images show the settings which were not easy to determine. See video of limit switches working. I should eventually redesign the x-limit switch mounts to get some more range of motion. Currently there is only like 3.5 inches in each direction. For future reference, Tab opens the jog menu in Mach3, the Settings tab (Alt+6) lets you override the limits to get unstuck, and the Diagnostic (Alt+7) tab shows pin states among other things. Also port 3 is the input pin port on the RNRMotion DLL and board.