Thread:Extension talk:LDAP Authentication/LDAP authentication on group OR specific user

I have LDAP authentication working either for all AD users or for all users in a specific group. I need to authenticate all users in a specific group OR a specific user but am having trouble doing so. I'm relatively new to this, so could anyone point me towards an example which shows this? I am authenticating against a corporate AD domain and cannot (and wouldn't want to!) creata a group specifically for wiki users.

Thanks.