Thanks Scott, I had seen that article about this.
Problem is I built the new site at example.dreamhosters.com and the current live site is still example.com at another hosting company I have no control over. I need to have them change the domain DNS to use ns1.dreamhost.com, etc., nameservers and have the domain point to the example.dreamhosters.com "proto" site now that it's ready to go "live".
The example given requires setting up an example.com account at DH and then build another site at example.dreamhosters.com and then have example.dreamhosters.com mirror example.com. I don't have example.com at my disposal.
Perhaps it means I set up a fake example.com account at DH and set the mirroring and hope it all hangs together when the DNS changes take.