Simulation of long-term exposure light drawing effect?

Dear high court of AFX magicians (who so brilliantly have guided me in tricky moments in the past years!)
I have another case where I am stuck, hopping somebody has a suggestion:

I need to create the equivalent of a long term exposure "light drawings.".
My subject is drawing with a flash light in my video and I would like to keep a nice solid line of what he was drawing. Tried layering an echoed image, but the light path doesn't add up to a solid line plus all other elements get too overexposed when choosing the appropriate layer behavior.
Any clue? Any plug-in suggestion or any other trick up your sleeves??

With deep appreciation for any hint, greateful as always,

Caspar

Found a link:

http://www.videocopilot.net/tutorials/q/ipod/

Andrew uses Trapcode Particular to do it, but you might be able to substitute CC Particle World if you don't have Particular.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA