the motor i bought was exi b1226 w/ continuous rotation.....
My project is very similar to what you are trying to do. It is an Arduino/processing based sentry gun, that uses a webcam and servo motors. Normally, I use standard servo motors - these go from 0 to 180 degrees, and you tell them a position to go to. However, I have also used continuous rotation servos - you tell them a direction to turn, and how fast to move.
So, I already have code that you can use for this: it is version 1.0 at http://code.google.com/p/airsoft-sentry-gun/downloads/list
All you will need for sensors are two buttons or limit switches, to detect the left and right turning limits of the gun. The servo motor you have will work just fine, with a gun-mounted webcam.
Feel free to contact me or reply with any questions!