[imp] Shared folders using Courier Imap?

[Andy Wright]

Simple question.... probably not a simple answer, but is it possible to 
use shared folders in IMP with Courier Imap?  I have generated imap 
folders flagged as shared but IMP tells me folder sharing is disabled..

I have;
'folders' => '',
'namespace' => 'INBOX.',
in servers.php per the comments,

I'm unsure what to put in the

// Folder sharing preferences

// folder sharing options
// set 'locked' => true to disable folder sharing
$_prefs['acl'] = array(
     'value' => '',
     'locked' => false,
     'shared' => false,
     'type' => 'implicit');

// End folder sharing preferences

   section of prefs.php - I've tried various setting but to no avail. Is 
this documented somewhere that I'm missing?

Has anyone managed to do this with Courier, or am I barking up the wrong 
tree altogether?

Cheers,
Andy.