Usefule link to play around with OID 11g

http://onlineappsdba.com/index.php/2010/12/14/how-to-add-custom-attributes-object-classes-in-oid-from-command-line-or-gui/

Enabling the schema manager in Active Directory

Another way to modify the schema is to edit the registry.

1. Start regedit.
2. Go to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTDS\Parameters registry entry.
3. Double-click Schema Update Allowed (of type REG_DWORD).
4. Set the value to 1.
5. Click OK.
6. Close the registry editor.