rails and HTML 5 offline application cache

I'm working on building an app that will also function offline using
new features available in HTML 5, including the offline application
cache. I am having some issues with defining the resources in the
cache manifest file, as it appears they all need to be defined in
routes.rb. For instance, if I want the app to cache all of the
javascript files in the public/javascripts directory, I add the path
to this folder in the manifest file, but then in my log I get a
routing error saying that there is no route that matches "public/
javascripts". There are lots of images, javascript and css files I
would like to be able to cache (along with some views), but am unsure
how to get these properly routed.

I'm wondering if anybody else has tackled this issue, or if anybody
has some ideas for how to handle it.

Thanks,

Simon