Can rails engine override main application's routes

I am writing a Rail 3 engine to add some marketplace functionality to an existing app. The existing app has an item description page and I am going to add some extra elements that will be used by the marketplace to that page. When the user visits the item page using the main app's route, I would like to use the engine's controller and view to render the page so that the new elements will be displayed. Effectively the engine will override some of the main application's routes. Can this be achieved?