I do not think you can get a Verizon 7750 to work with Bell or Telus, unless you can get Verizon to somehow unlock the BlackBerry unit.
You will need to contact Verizon to see if your BlackBerry can be unlocked for use in Canada.
At the moment, I believe that the best BlackBerry carrier is Rogers in Canada, while not as good as Bell in other ways, they are quicker with the latest BlackBerry models (Rogers had color for more than half a year than Bell did) and the 7280 CPU performs faster than the 7750 CPU due to less overhead, and the new 850 Mhz band in the 7280 works excellently and improves the coverage more or less equal to Bell in the Ontario area (at least for data reception; not sure about voice though! People say CDMA has better sound quality, but I have a data-only plan with my BlackBerry). I am using a former broken-and-repaired Cingular 7280 on Rogers at the moment, Cingular is the easiest USA carrier to bring phones to Canada, since their phones come unlocked.
However, check with Verizon to see if the 7750 can be used in Canada. I'll have to leave it to others to see what the best procedure to unlock a BlackBerry would be (HoFo might be a good place to check for Verizon's stance on unlocking.)
If you can get an unlock code for the Verizon BB 7750 you'll have to use it on Bell Mobility's network, Telus under no circumstance will allow an unlocked phone/device or foreign IMEI unit on their network.
If it helps any my wife had a Kyocera 7135 before she hi-jacked my BB 7280 from me and that kyocera was from Alltel a US CDMA carrier which was unlocked and Bell was able to get it running on their 1x CDMA network.
As Mark said and though Rogers does have its down side their probably the easiest to deal with, dedicated dept. to support the Blackberry and they cuold care less about unlocked devices on their network.
I am currently a Bell Blackberry customer and frequently visit the US. Can I use my 7135e on Verizon's network (i.e. get the unlimited data plan for $60). I just don't want to spend $8/MB roaming with Bell while in the US!!