MySql on another Server

[pgentoo]

I have an existing setup with one server, but am looking to break out mail/db into separate servers soon. I dont want to break existing client sites that are connecting to mysql through "localhost", via unix socket currently. How have you taken care of this? just force everyone to switch to using mysql.domain.com over TCP or something first, then make the actual migration later?

id be interested to hear what others have done...