You need to use Samba version 3 for it and it will defeat the purpose of SME as this will break most of functions of SME.
You may be better off with generic minimal install of standard Linux Distros. Update it to Samba 3 and manage file sharing manually or via webmin or similar and users via AD. If you need advanced security, use file system with ACL and extended attributes support.
SME server is just not there yet and designed for different market.