The PIR sensor comes with a 3-pin connector with bare wires at one end. We'll need to do just a little soldering to create a connector that will plug into the MonsterM4sk.
Find your 3-pin JST connector and cut it in half, so you have bare wires on one end.
Slip on some heat shrink and solder the 3 wires to the sensor connector:
You're done! That was easy. Plug the sensor into port D3 (on the right as you look at the back of the Monster M4sk).
Once you've got your software loaded and the sensor plugged in, you can adjust the "sleep" delay using the screws on the back of the sensor.
Turn them counter-clockwise as far as they will go. Wave your hand in front of the sensor and the eyes will come on. Hold still and they will slowly close after just a few seconds.
Use a screwdriver to turn them clockwise until the "awake" time of the eyes is right for your project. They're pretty sensitive so just turn them a little bit and test until you get it just perfect.