Unlocking Ifixit's replacement logic boards to foreign carriers

I'm considering purchasing one of Ifixit's GSM IPhone 4 replacement logic boards, which are listed as locked to AT&T/T-Mobile.

Can (and how) these boards be unlocked for use with another carrier? The phone I'm repairing (replacing more like) is attached to Koodo (a Telus subsidiary) here in Canada.

Intuition says I'll just be able to bring my phone (in effect a new AT&T or T-Mobile phone from the US) to my carrier and ask them to unlock it, and as I've no account with either AT&T/T-Mobile this is my only option.

Has anyone any similar experiences getting foreign phones unlocked without transferring them from other carriers?