Yeah, I've done it a couple times... Just leave yourself a lot of extra time and you should be ok. If you can get a hold of some of the jumpseat forms ahead of time, you'll save yourself a lot of trouble... (And it's MUCH worse getting out of Canada than going in...) (The gate agents up there have no idea what "jumpseat" means...) Even the Xjet agent in YOW I used the other day looked at me like I had three heads....
Persistence pays off though... And luck helps...