This small wire connector is made to allow the LED ground to be connected to the normally closed(NC) or the ground connector on the microswitch.  If you use this to connect to the NC microswitch tab, the button will be illuminated unitl it is pressed and then it will turn off.  If you connect it to the ground, you can connect the button ground harness to the .187 tab on the connector and use one harness for both the LED and your switch!