autocreate shared folders during delivery?

[James Ralston]

We have a high-volume mailing list that we want to have delivered to a
series of shared folders based on the date that the message is
received:

    sharedfolder.example-list.2009.01
    sharedfolder.example-list.2009.02
    sharedfolder.example-list.2009.03
    ...
    sharedfolder.example-list.2009.04

We may need to get it down to the granularity of a single day; e.g.:

    sharedfolder.example-list.2009.09.01
    sharedfolder.example-list.2009.09.02
    sharedfolder.example-list.2009.09.03
    ...
    sharedfolder.example-list.2009.09.15

Now, on the mail hub, we have a process that expands the
"example-list" alias appropriately based on the current date/time.
E.g., on 2009-09-15, this:

    example-list at example.org

becomes this:

    +sharedfolder.example-list.2009.09 at imap.example.org

...when using a "monthly" expansion rule.

The problem we've run into is that there doesn't appear to be any way
to get Cyrus to autocreate the shared folders on the fly during
delivery.  (The autocreate patches from the University of Athens
handle autocreation only for regular user accounts.)

Having someone manually create the folders in advance would have
overhead, as well as be subject to human error.  Trying to script it
would also be problematic, because storing authentication credentials
would be required.

Has anyone encountered a need to do something like this before?  If
so, what did you do?