[Zope] More than one Zope site for one Zope installation ?

[lstep@mail.dotcom.fr]

I have several users who want all to have access to Zope.
These users have each a domain foo.org, bar.org, but it points
to the same machine, with, currently, one standard Zope installation
(with PCGI with Apache). They currently use standard Virtual servers
functionnality from Apache.
Now I'd like to allow them to have a zope access to each of them.
As they want http://user.org/ to be their base url, I need to keep
the virtual servers.

I think my solutions are:
Make several copies of the Zope tree, and with each one, make a
database, and point the the good zope pcgi in each virutal server.
It is not an acceptable solution for me, as having several Zope instances
gets a lot of ressources ;-(

Make only one Zope tree, with only one database. Create a folder in
the database for each user, and make each virtual server map '/' to
the user folder. I tried this, but I had big problems caused by the
fact that '/' is not /user_folder :-(

Is there something possible with ZServer (without Apache)? Is there
some "virtual server" implementation (making a database for each user, or
all users in the same database)?

Some time ago, I saw a thread about a variable "INSTANCE_HOME", what is
it about, and is it implemented in V.1.11 ?


Thanks,
Luc