Passenger and multi-site application

Hi list !

I am trying to test zena ( with passenger
( The basic setting is "point apache to the
'/zena/public' directory. This is fine for a single site application
but zena is a little different:

Cached content => '/zena/sites/'

Other requests => '/zena/public'

Does anyone know how to configure this ?

Many thanks for any help...


Basically, the question boils down to:

How to configure "RAILS_ROOT" in passenger ?