You'll need a nice server and plenty of memory to do it, but the best way would be to use your favorite virtualization software and run a separate ip address, msg, npc, and mysql server on a virtual server. Configure your account server configs for the second server with the new ip. Your oem.dat will use the same ip as your first server because that is where the accounts are located. That's the basics.
I heard of someone trying to change all the ports on the binaries but I don't think it ever made it to a production environment.