This would be a challenge. I spent several weeks getting Solaris 10 to use Windows 2008R2 active directory. There were special configurations for pam.conf, krb5.conf and ldap.conf (on Solaris it's ldap_client_file and ldap_client_cred). I also spent a good amount of time getting Solaris to work with RedHat Identity Management, too, when I thought that might be a better answer. It's a lot of trial and error and searching and reading and testing and repeating. I would lack a compelling reason to want to do this on a Pi, however, so I would probably be prone to abandoning the project early on. But that's me.