I did EXACTLY what has been mentioned above... Flying from YYZ (Toronto) to CDG (Paris) and back in the summer of 2003. I had the clear ziplocks, I had the film ready, I was polite and patient, I had a few rolls of TMZ in the bag just to pursuade the checkers to hand inspect.
Toronto granted the request - although I had to plead my case a bit... Paris made me take out the few rolls of TMZ and the rest had to go through (including ISO 800 colour neg) - no exceptions. No film was damaged though. Best thing you can do is try to minimize any hassles by following the above, but more importantly be as friendly as you can with the request.
Have a wonderful trip,