[Samba] howto? howto switch domain controllers in an ldap directory?

[Christ Schlacta]

I've got an ldap directory, but no PDC yet.  I want to set up a test 
PDC, and once things work, I want to be able to set a more appropriate 
system to be teh PDC using teh same login informations (replica of 
existing authzn databases).  where's the documentation of how to do 
this?  what do I need to know about this process (I'm not sure what it's 
even called >,.,<

in case I wasn't clear above, I want to just be able to "flip a switch" 
(in the proverbial sense) and switch PDC on an existing ldap directory 
without having to purge it or migrate data or anything else so complex.