Using Active Directory Authentication in mojoPortal is relatively easy.
1. first get the site working using the db authentication, ie. normal installation
2. Login as Admin, go to Member list page and click gear icon next to admin user
3. change the admin user name to a name that is also an AD user. For example if my AD user name is jaudette I would change it from admin to jaudette
4. logout and then login again using the new user name
5. Click the key icon to get to admin menu and choose Site Settings
6. Click the security tab then the LDAP tab (well tabs are not in the 2.2.3.9 release but are in svn trunk and in the soon coming release). skip this step if using the current release, just scroll to the ldap section
7. Enter the host name of the AD server
8. Enter the AD domain name
Click Save to store the basic settings. Then check the box that says Use LDAP for Authentication and enter your windows password in the password box.
Click Save aain and this time it will test the authentication against AD. If it fails it will not save the setting Use LDAP for Authentication. This is to prevent you from getting locked out of the site.
The Root DN setting depends on how your Active Directory schema is configured. The above worked for me using a clean install of Windows 2003 server and following the defaults when installing Active Directory.