Best 301 redirect method for Subdomains with Domain Mapping

Hi -

We have a mutli-site setup where we have domains first set like this:

We are using the WPMUdev Domain Mapping plugin at times to later change the blog's subdomain to:

So, we are after the most efficient 301 redirect solution to affect this change and that will work with the Domain Mapping plugin.

I am aware of htaccess, php function, and plugin solutions and have read a bit about these here on the forums, but need to know best recommendation for the above configurations with Domain Mapping in place.

- Scott