Possible? Set the value of a custom field based on the domain option selected

[writeclickmedia]

I've got a website + hosting product setup so that the first step is to choose between: A) Purchase and register a new domain -OR- B) Use an existing domain.

 

It would be nice to direct new customers to their "http://purchaseddomain.com" as step one in the welcome email if they choose A), but if they choose B), send them to: "http://124.34.02/~username/" instead (as per the usual temp URL email field "http://{$service_server_ip}/~{$service_username}/).

 

Anyway to do this? In a .tpl or otherwise?

 

The variable in question seems to be {$domainoption} but I can't find anyway to access it from other .tpl files.

 

Thanks for any suggestions.