Changing APN settings without a WiFi Connection

I just bought an AT&T iPad 2, but live in Canada. Thank you so much for your service. I look forward to using it to enable a Rogers Canada plan when I am back in Canada (I didn't realize that Apple had hidden the APN settings when I bought the iPad).

One question I have though is whether or not it is possible to save the config file on the device somewhere so I can change APN settings dynamically without a WiFi connection. I drive back and forth between Canada and the US, and I would like to be able to change my SIM card as I cross the border so I can use local plans on both sides of the border. It would be nice to be able to do so without needing to find a WiFi hotspot first. I suppose when I drive from Canada to the US, I should be able to just remove my Roger's mobileconfig file and hopefully it would revert back to the AT&T settings. When I drive back into Canada, I would need to re-install the Roger's mobileconfig file. If I had the file stored locally on my iPad (maybe through a service like Dropbox), could I click on the mobileconfig file to install it? If so, how do I get the mobileconfig file onto my Mac so I can put it in Dropbox?

Thank you so much!

Ron Miller