I was working on this for a while, until the plane was sold out from under me. I wonder if it was you.....
Anyway, first, the Owner of Record in Canada must have it de-registered with Transport Canada. You will need a copy of the deregistration notice from Transport Canada(their version of FAA reg branch). Next, you'll need a bill of sale from the last owner of record that is acceptable to the FAA(this is important, they want specific things in the bill of sale). You can then bring it into the US, and you will deal with the US customs on import fees, and any duty owed. Once in the US, it will need a condition inspection(it's an EXP plane), then finally it will need a airworthiness inspection for it's AW certificate from a different person than did the condition inspection.
I have a few questions. Was it built from a commercially available kit, a copy of which has been built and registered in the US (like a Challenger, or something)? Would you consider taking the wings and engine off, and import it as 'aircraft parts'? If you would I think customs would be easier.