Did some reading. It's a photodetector, which means there would be some work to do in order to hook it up to your IPAQ.
If it's just a photodetector, we'd have to figure out if the beam-break makes a digital high or low, then either feed that into an inverter or leave it alone and shove it right into the IPAC.
It's all 5v, so you'd feed the device on the left +5v on red and Ground on black (2-pin). This is the emitter.
The device on the right (3-Pin) should be +5v (Red), Ground (Black), and Detect (White).
Hook up power and ground, then use a meter to see what the white wire does when the beam is broken vs. unbroken. If it goes to 0v when broken, you're in business and can hook the white wire to your IPAC directly. If it is normally 0v and goes to 5v when the beam is broken, you'll need an inverter.
Edit: VC3 Cab Manuals if you're ever interested.
http://www.sauservice.com/manuals/VirtuaCop3/VC3main.html