Monkey patching a Gem method in Rails 3

Question

I'm willing to use friendly_id gem with Firebird, but I need to override a method that implements a specific SQL function with code related to Firebird.

I've created the file config/initializers/friendly_id_monkey_patch.rb containing the following code:

module FriendlyId
  class SlugGenerator
    def conflicts
      #my_code
    end
  end
end

However the application keeps executing the original gem's method, ignoring my patch. What could be wrong?