[imp] Displaying quotas

[horde at corwyn.net]

I'm trying to get imp to display quotas by modifying
./imp/config/servers.php by (roughly following the instructions at
http://oli.lugh.ch/quota-workaround.org.html and looking at
/var/www/htdocs/horde/imp/lib/Quota/maildir.php

in maildir.php the instructions read:
* Requires the following parameter settings in imp/servers.php:
  * 'quota' => array(
  *     'driver' => 'maildir',
  *     'params' => array(
  *         'path' => '/path/to/users/Maildir'
  *         // TODO: Add config param for storage vs message quota
  *     )
  * );
  *
  * path -- The path to the user's Maildir directory. You may use the
  *         two-character sequence "~U" to represent the user's account name,
  *         and the actual username will be substituted in that location.
  *         E.g., '/home/~U/Maildir/' or '/var/mail/~U/Maildir/'


I'm trying to set the path, but I'm supporting multiple virtual 
domains, and my path is
/var/spool/mail/domain/user/Maildir

if ~U represents the account name, how do I represent the domain?

Thanks

Rick