^^^^^ What Kevin said.
If you're the kind who likes tutorials, Andrew Kramer has a couple that, while
looking totally different from what you're going for, use a very similar technique to accomplish it.
http://www.videocopilot.net/tutorials/
Check out
#18 "Light Streaks"
#25 "Light Streaks 2"
Kyle Hamrick
Editor/Motion Graphics Artist
www.kylehamrick.com