[horde] prefs_hook for an horde application - is it possible?

[Matthias Rolke]

Hi there,
i'm currently trying to determine the value of a user preference by a
hook.
This is pretty easy for preferences in the scope 'horde' and thus being
configured in horde/config/hooks.php, horde/config/prefs.php.
But in my case, i want to determine a preference value for an horde application.

So, i created a prefs_hook in my "application/config/hooks.php" and enabled it in
"application/config/prefs.php" like it is described in "horde/config/prefs.php".

But the problem, afaik, is that the preference hooks are only being executed
on login.
"NOTE 2: Preferences hooks are ONLY executed on login." (horde/config/hooks.php)

And sadly on login, the application preferences are not being loaded.

So, my question is the following:
Is there any possibility to determine a value for a preference value for
an application?

If you're interested, here is my exact case:
 * I'm using Kolab as the source for addressbooks in turba
 * The default_dir for every user should be his/her personal Kolab addressbook, stored in the personal Kolab mailbox
 * The source type name for that personal addressbook is "kolab" (see turba/config/sources.php), but for the user
   the default_dir value has to be an uid like user at example.com (the name of the kolab mailbox)
 * therfore only a hook would determine the right value for the "default_dir" preference for each user

Thank you very much in advance!

Sincerly,
Matthias