[How To?] How to migrate forum from subfolder to a subdomain?

[badlydrawnben]

Hi, 

I can't find any definitive instructions on how to migrate a forum from a subfolder to a subdomain.
So the forum is at mysite.com/forum and I want to move it to forum.mysite.com

I can create the subdomain DNS record and set the A record accordingly.

I'm looking for a list of all the files and database tables that need to be updated with the new url. Can anyone point me in the right direction?

Thanks.