I don't believe there is any method to directly do what you suggest. The FAA certificate is issued by the FAA in accordance with provisions in
14 CFR 65 Certification: Airmen Other Than Flight Crewmembers and is transportable between companies.
The Canadian dispatch certificate is not transportable and, as I recall, is only valid at the company from which it was issued.
R745.110 - Flight Dispatcher Qualifications
Qualified company flight dispatchers shall possess a flight dispatcher's certificate. The certificate, granted by an authorized person who is an employee of the operator, signifies successful completion of the Transport Canada approved flight dispatcher course. The operator shall advise the Minister of the names of people in the operator's employ who have been granted certificates. Similarly, the operator shall advise the Minister of dispatchers who no longer hold a valid certificate. This would be due to loss of competency or ceasing employment with the operator.
Canadian Aviation Regulations (CARs) and Commercial Air Service Standards (CASS) - Part VII - Subpart 5 - Guidance Material
Perhaps some day there will be provisions in
Part IV of the Regulations to license dispatchers (just as they do for flight crew members, air traffic controllers and aircraft maintenance engineers).
If there is a method to do a transfer, you should be able to get an answer at one of these two places:
Transport Canada Civil Aviation Communications Centre
CanadianDispatchers.org