Connecting a self-powered PIR sensor to Arduino

Hi,
I own a "traditional" self-powered PIR motion detector and Im wondering if I can connect it to my Arduino breadboard, and how.

This device has its own power supply (I believe it's 9V) and two connections for output wiring.
I'm looking for the proper setup for connecting everyting to an arduino.

So far I have only found the adafruit PIR tutorial, which uses a PIR sensor with 3 outputs, one for power.
Any ideas?

E.

Have you hooked a multi-meter to the 2 output pins to see what type of output you get when motion is detected?

Most likely the two pins are connected to each other in the PIR when motion is detected.
If thats the case you can connect to ground, the other to a pullup-enabled digital input pin and just watch for a low occurring.