nested resource routing

I am using rails 1.2.6 and I'm trying to define a RESTified route that
will work for a nested resource. I have a permission resource that I
want to be nested into all my other resources. If I wanted to nest
permission specifically for say my customer resource then that would
simply be:

map.resources :customers do |customer|
customer.resources :permissions
end

and this will give me url methods such as permissions_url(@customer),
permission_url(@customer, :permission_id) etc.

However what I want to achieve is a generic route definition that will
give me this functionality across all my resources. Something possibly
looking like:

map.resources :any do |any|
any.resources :permissions
end

where any can be any resource and have url methods like
permissions_url(@books),
permission_url(@itineraries, :permission_id).

Any ideas will be appreaciated. Thanks.