Define routes for Helpers accessed via RABL

Dear Reader,

I'm trying to define routes for my helper, so that I can call them from
my RABL template(for Api Driven Development) with appropriate arguments.

With reference the Railscast link:-
http://railscasts.com/episodes/322-rabl?view=asciicast , its clearly
mentioned we can pass objects in the helper methods having a defined
route path.

I referred to the below link on how to create routes for my helpers:-

http://stackoverflow.com/questions/6470656/how-to-define-own-routing-helpers-in-rails-3

But I couldn't understand it clearly like as to where do I define or
mention the method name whose route path I want to define. I want to
define the path of a helper method and pass two arguments to that
method. Can anyone please tell me how is it exactly done in Rails as
part of routes.rb .

Thank you.