acts_as_ferret: using an index outside of the application

Hello,

Does anyone who has worked with acts_as_ferret know how to point the
search to an index outside of the application?

I've tried changing the environment.rb:
module FerretConfig
  include Ferret

  INDEX = Index::Index.new(:path => '/my_other_applications_index/
index/')

end

"Asked for a remote server ? true, ENV["FERRET_USE_LOCAL_INDEX"] is
nil, looks like we are not the server
Will use local index."

Many Thanks