You will be removing the yellow and green wires from terminal 1 and 2 from step 2

Re-crimp the wires and using a 3 pin connector. Connect it to E1_STOP on the Duet

Polarity of the green and yellow wire doesn't matter.

Add the commands for "output_pin psupower" "gcode_macro M80" "gcode_macro M81" and "gcode_button power_on" to your printer.cfg

I've uploaded my config to my github