BGR walks you through the steps necessary to make your iPad work with various providers in Canada. As the old saying goes, "Everything is easy when you know what you're doing." BGR has done the hard part for you, including figuring out the various APN settings for different carriers.
The most challenging part of the process will be cutting down a SIM card to (mini) size. There are lots of instructions around to help you but in the end they're your fingers and your card, so be careful.
The instructions cover Bell, Fido, Rogers, and TELUS.