dovecot - Jul 2013 - Creating an authenticated user master user

dovecot --version
1.1.18
mbox format

We are trying to migrate from dovecot to another imap server and need some
help migrating the user data to the new server.  We have written a perl
script to migrate the data but it seems that we need an "authenticated or
Master user" in order for the script to access the user mail boxes without
the users password.  We are using PAM authentication, and root does not
have access to the user's mail boxes.  Any help would be appreciated.
Chris