We haven't tested it enough to say it's a sure thing, but from a quick test we did a few months ago, this should be easy to setup. When you create your Facebook application, simply use the "Base Domain" setting, and you should be good to go. We'd love to hear how it goes for you though, or if you need to do anything special.
For more information:
wiki.developers.facebook.com/index.php/Base_Domain 
Using with multiple subdomains
