[imp] Listing users in the Horde administration interface with IMP as the auth backend and Courier as the IMAP server

[beau]

I am trying to get the Administration -> Users function to list the
users from IMP, which is my authorization backend.
 
Currently there are no errors but it does not find any users.
 
I stole the defaults from the cyrus example but I have no clue what to
use for userhierarchy, or if Courier supports listing user mailboxes at
the root level (which I believe is the method used to build the user
list).
 
Any help would be much appreciated!
 
I'm using Horde 3.0.5 and IMP 4.0.3.
 
This is from my servers.php:
 
$servers['imap'] = array(
    'name' => 'IMAP Server',
    'server' => 'freebsd.zoicstudios.com',
    'hordeauth' => false,
    'protocol' => 'imap/notls',
    'port' => 143,
    'namespace' => 'INBOX.',
    'folders' => '',
    'admin' => array(
        'params' => array(
            'login' => 'mylogin',
            'password' => 'mypassword',
            'userhierarchy' => 'user.'
        )
    ),
    'maildomain' => 'zoicstudios.com',
    'smtphost' => 'freebsd.zoicstudios.com',
    'smtpport' => 25,
    'realm' => '',
    'preferred' => '',
    'dotfiles' => false,
    'hierarchies' => array()
);