[Samba] Samba 3 upgrade

[Chris]

Would like to do upgrade of couple of older SuSE 7.3 systems currently running 
Samba 2.2.7 (as a PDC) to Samba 3.0.8. There are no RPM's availalble but I 
would rather compile the source anyway and place Samba3 under the 'local' 
hierarchy (such as /usr/local, etc.) leaving the Samba2 virtually untouched 
in case I need to fall back for any reason.
Is there a documented procedure for doing this safely?
What tdb's need to be saved and/or copied for the new install to take over the 
duties seamlessly?
How does one maintain the sids, etc. so that the change is transparent to the 
domain members and machines?
Any other assorted details or gotcha's would be useful as well.

Thank you.

Chris

PS. We do plan server upgrades within the next 6 months but right now we need 
to move ahead to clean up the XP issues with the older version of Samba.