2337 did something similar in 2012 - we had 3 LEDs on our robot (red green red) that helped us line up during set up. The LEDs worked like this:
Two outside red lights on: Can't see a target
Only left red on: Robot is pointed far left from the target (move it right)
Left red and green on: Robot is just left from the target (move it right)
Green: Robot is on center
Same rules apply for the right red LED
You can find our code on GitHub here
https://github.com/Team2337/2012ReboundRumble. If you use LabVIEW, check out VisionProcessing.vi