Override Rails3 CSS stylesheet and image path

gistfile1.rb

module ActionView
 module Helpers
   module AssetTagHelper  
     
     def stylesheet_path(source)
       compute_public_path(source, "stylesheets/<some sub dir here>", 'css')
     end      
     alias_method :path_to_stylesheet, :stylesheet_path

     def image_path(source)
       if File.exists? File.join(Rails.root, "public/images/<some sub dir here>", source)
         compute_public_path(source, "images/#{AppConfig.get 'assets_subdir'}")
       end
     end
     alias_method :path_to_image, :image_path


   end
 end
end