RESTful routes and resulting urls

if I have the following in my routes.rb:

map.resources :product_categories

it provides urls such as:

/product_categories
/product_categories/1
/product_categories/1;edit
etc.

and uses the ProductCategories controller.

how can I keep the same controller (and model) but set up the resources
so that I can have any abitrary url point to the existing controller,
much like specifying the controller with the old style routes?

-felix