[Dovecot] [dovecot] Question about master user and PAM with dovecot 2.0.12

Is it possible to allow master users to be authenticated against PAM? Something like:

passdb {

driver = pam

#args = /etc/dovecot/passwd.masterusers

master = yes

#pass = yes

}

and then have a userdb which qualifies what accounts are master accounts but doesn't have passwords?

Thanks, Jonathan