dict lookup from quota plugin

I am having trouble with using a custom daemon listening on a socket together with the quota plugin. My configuration is:

quota = dict:User quota::dict:/tmp/dovecot-proxy-dict::

The problem is that dovecot sends keys without usernames, for example:

priv/quota/storage

Is it possible to get around this limitation without code modification? Also, is it planned to support the "new-style" userdb/passdb lookups from other plugins?

-- Bj(/)rnar