Hi
You can't edit users that exist in another LDAP Directory. Only an administrator on the other LDAP server locally can do that.
The way this usually works is you augment what is available on the AD with OD MCX for macintosh clients authenticating with AD accounts and mounting AD published home folders.
To that end once you have successfully bound OSX Server to AD and promoted to OD Master with Kerberos stopped you should be able to view all users and groups that exist in the AD node by selecting the Active Directory/All Domains node. You then create a group in the /LDAPv/127.0.0.1 node, drag users or groups from the AD node into the newly created group and apply managed preferences that way.
There is a wealth of information about this available from:
http://www.bombich.com
http://www.macwindows.com
http://afp548.com
Hope this helps, Tony