how to redirect a subdomain blog to an external URL?

One of my oldest and most serious bloggers moved away from us and has his own domain now on his own hosting. As a parting gift I'd like to redirect all requests to his blog to his new domain, what would be the easiest way to do that?

I know how I can use .htaccess to redirect domains but does this also work for subdomains? I guess it does? For a complete top domain redirect I'd use:

redirect 301 / http://www.you.com/ but I guess for redirecting a subdomain I need some more knowledge so can someone suggest the best method to do this?

I'd prefer a .htaccess solution or maybe an internal setting in his blog, I mean is it possible to edit his blog's settings and have it redirect to another URL? Or maybe plugin based? Or could the Domain Mapping plugin be abused for this? Its just a "temporary" thinggy for i.e. 6 months till his followers have followed him to his new blog?