Create a user in:
ou=Administrators, ou=TopologyManagement, o=NetscapeRoot
Set ACIs to allow only this user or all users in the Configuration Administrators group to access the Directory Server where the product’s configuration directory is stored.
Specify entire DN during Core installation.
For more information about managing access controls in the Directory Server, see Chapter 6, Directory Server Access Control, in Sun Java System Directory Server Enterprise Edition 6.1 Administration Guide