Hi All
Went through yesterday and it was all really easy. The booth is at the top of the escalator at the end of the terminal that has the Priority check in for AC. If you are coming from the garages or the tram go right as you enter the terminal, after the bridge, and up those escalators and it's at the top. The scan code is on a business card they give you and it says "one time code" so I'm guessing it can't be re-used. It was simple to get, I showed them my Aeroplan Express card and they handed me one - so no need to have booked on the card, just have one in your possession.
Since this is so casual I wonder if you couldn't grab one from them on arrival when they are open and use it the next day or a few days later when you are leaving, it may solve the problem of them not being open early in the morning. You may even be able to talk them into giving you a few in advance.
As it turned out there was no great line anywhere, the regular line was basically empty from the first agent to the second agent at the security area. This was on a Wednesday at about 3:00PM though.