Bob,
There are a few threads that might help you with this, here's a couple that covers the steps in some detail (and may scare you into shipping them to a vendor to do it for you - unless you're comfortable welding magnesium, and your significant other doesn't mind you using the oven to do some baking.
Campi Wheel Reconditioning
Here's a step-by-step description of one member's experience (in his case there was no welding) ...
Wheel Refinishing
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