Tricky quota question

[Lars Hansson <lars-openbsd-misc_(_at_)_unet_(_dot_)_net_(_dot_)_ph>]

Well, it's tricky for me at least.
Here's the thing:
I need to implement some kind of quotas with mod_dav. Since mod_dav doesnt have any built-in quota support I figure I have to do it the filesystem way.
Somehow.
mod_dav needs the directories to be owned by the webserver user (www) so user quota support is out.
Is it possible to use something like a union or null filesystem for this? I basicly need one filesystem, with quota support, for each directory handled by mod_dav.
Or, I guess, it could be done with group quotas since mod_dav doesnt care about the group ownership (as far as i can tell).
Anyone tried something like this?
Right now I wish there was such a thing as "Directory Quotas" or something...

-- 
Lars Hansson                  Technical Consultant/System Administrator
UNET, Inc.                    Makati City, Philippines
e-mail: lars_(_at_)_unet_(_dot_)_net_(_dot_)_ph