Hi Paul, here is the main resource for importing vehicles into Canada: http://www.tc.gc.ca/eng/motorvehiclesafety/safevehicles-importation-index-443.htm
The import regulations are determined at the federal government level, but each province can determine whether they will accept RHD vehicles or not. Inter-provincial transfers (i.e. register the vehicle in one province, then re-sell or transfer to another) also will require safety checks. Insurance requirements to be able to register a vehicle also vary from province to province. British Columbia is generally the most liberal in accepting kit and RHD cars from an insurance and registration perspective, Alberta is OK, Ontario seems to be more difficult and Quebec possibly the hardest.