I would like to add a motion light sensor to my door and garage lights. Can I just cut into the middle of the light system and add the sensor, or do I have to re-wire all the lights?

The switch is located at the door and there are two lights before where I want to put the senor, followed by two more lights at the garage. I have easy access to wiring in the garage and could add another cable from end of lights back to the sensor.

If someone could add a picture diagram on how to wire, that would be helpful. Thanks