[Centos] Upgrading from 3.4 to 4.0 beta X

Please forgive me if I missed something, but I've searched all over in hopes of finding something documented on a procedure to upgrade a Centos 3.4 system to the beta. I've got the DVD burned and am testing the process on VMWare. All I could figure out how to do was install over the existing partition without formatting, but this was quasi-disastrous so I 'reverted' my VMWare drive to the prior state. Is there some way to reconfigure yum.conf, GPG keys, etc. so that it will pull down the changes? Or, is there a way to 'upgrade' the system using the CD as a source? Any help would be appreciated. I was hoping it was as simple as the upgrade from 3.3 to 3.4, but I couldn't find anything out there.

Thanks,

Mike