If you want to end up with a British Columbia registration in your name here's more information than you might really want to know.
Both you and the seller need to fill out and sign a B.C. type of transfer form known offically as a "APVGT Transfer/Tax Statement of Vehicle Origin". The seller can easily pick one up, complete his part of it and send it to you.
The seller also needs to provide you with a signed tear off portion of his old registration.
You would fill out and sign your portion of the transfer form. Skipping over some complications for the moment, the completed transfer form (and the old registration) could be sent back to B.C. and presented by somebody at any "Autoplan" office in B.C. Two sales taxes would have to be paid on the selling price (12% total) plus a further fee. This would yield a new B.C. registration in your name but no licence plate. In B.C. a new plate only issues if you buy at least the minimum required liability insurance for the vehicle. Such insurance would not be valid in S.A. by the way.
O.K. now for the complications. Firstly, since you would not be personally present in B.C. to carry out this process, whoever goes into the Autoplan office for you would need a type of power of attorney authorizing them to effect the transfer on your behalf.
Next, the transfer form does have a space for you to write in a B.C. driver's licence number. I'm not sure if this is compulsory. People do come into the province from elsewhere and buy vehicles presumably while still on foreign driver's licences.
Next, the transfer form does, of course, require an address.
To find out out what the power of attorney looks like, and if you must have a B.C. driver's licence and if you require a B.C. address I suggest you root around on the Insurance Corporation of B.C. website which has a wealth of information. The URL is ICBC - Insurance Corporation of British Columbia
. This government insurance company handles all vehicle registrations as well as vehicle insurance.
If you managed to jump through all these hoops and end up wih a B.C. registration in your name I'm not sure what you could do with it given that you're is S.A.
As I said, perhaps more than you wanted to know.