[Dovecot] user database clarification

Hi, this question gets back to a thread I started back on July 8th.
(gosh how time flies)

I still am not clear on why PAM is not supported for the user database.

I'm in an environment that has users both in local flat files (/etc/passwd and /etc/shadow) AND in an LDAP database.

Is it possible for this set up to work with dovecot? (both local and ldap users have imap/pop?)

I'd prefer to just have Dovecot use PAM for user db and the password database so that I can configure PAM to try both local users and LDAP users.

Thanks a lot. -jared