C# Novell eDirectory Password Authentication

I have a VS2008 c# .NET winform application that can authenticate against ActiveDirectory easily.? It can also authenticate a user at a root organizational level in Novel eDirectory.? I need it to be able to do a recursive search (with an LDAP command) to search all nested organizational units (OUs) in the LDAP tree. Currently, the search uses a DirectoryEntry search for ActiveDirectory and for eDirectory we use LdapConnection/NetworkCredential .NET classes authenticate a user (basically ask the LDAP, given user ID and password, to verify the user is an active valid user/password combination).? For eDirectory we use a formatted search of "cn=<userid>, o=<organizaitonunit/domain>".? That works fine for a user added at the highest level, but how do I format the string (or use another .NET class/method) to search all sub-organizations (OUs) that are included within the? base organization?