It's not possible at the moment within the script. You might be able to setup a 'direct' file server entry, which is actually located on your same server. i.e. via another vhost. Then that would have it's own domain name. However it's a lot of 'jumping through hoops', you'd need 2 copies of the code installed aswell.
If you add something to the RFCs I'll ensure it's reviewed for the next release. An option in the file server settings via the admin area would probably work.