light drawing project problem

i'm creating a project using the isight and what i want to do is to take a LED and use that in front of the camera in a dark room and have jitter show the progression of the image that you make with the LED. so basically you would see a black background with streaks of lines created by the LED when it moves. so at the end you see a an image that was created in a certain amount of time by moving the LED. i hope that i explained this clearly enough and i hope that you guys can help me out. thanks