Routing problem: extending matched route segment

Hi all,

I would like to route a request to a specific domain
('request_routing' plugin installed) to controllers living in a
subfolder for that domain like this:

http://www.mydomain.com/home/index
:controller => 'mydomain/home', :action => 'index'

I would like to use a general route like '/:controller/:action'

Is it possible to somehow access the string matched by :controller,
extend it and use the extended string as the controller, like the
following?

# mydomain routes
map.with_options :requirements => { :domain => /^mydomain/ } do |
mydomain>
    mydomain.connect ':controller/:action', :controller => "mydomain/
#{controller_match}"
end

Thanks for any hint!
Ingo