I'm not sure what you are asking, but take a look at these blog article on a step-by-step R2 deployment. The initial steps cover prepping the AD forest/domain for OCS.
http://www.shudnow.net/2008/06/08/office-communications-server-2007-enterprise-deployment-part-1/You typically don't have to so anything special related to replication of OCS-related attribute and information, unless specific customization has been performed in your particular environment.
Jeff Schertz, PointBridge | MVP | MCITP: Enterprise Messaging | MCTS: OCS