Talk to Seggy as he has first hand experience.
Here in Canada, we don't have a "Cass" system. For people that jumpseat on Jazz/AC they have to fill out a jumpseat coupon, which the captains (and sometimes FOs) carry with them. The captain will check your ID. I think there's a number you have to call to list yourself on a flight first, and this will allow you to check-in when you arrive in order to get a standby boarding pass so you can go through security.
When I fly on Jazz/AC, I book myself through our employee travel site, so I have never used the jumpseat system, although I have had US pilots on our flights (I had a Republic pilot not too long ago, and Seggy jumped with us as well).
You cannot sit in the jumpseat itself either, a seat in the back has to be open.