module_for_plugin.rb

class Asset < ActiveRecord::Base
  acts_as_taggable_on :tags, :people

  # FIRST ATTEMPT
  def tag_list=(new_tags)
    set_tag_list_on('tags',new_tags.downcase)
  end

  def person_list=(new_tags)
    set_tag_list_on('people',new_tags.downcase)
  end

# SECOND and successful ATTEMPT
  module HackTag
    def set_tag_list_on(context, new_tags, tagger=nil)
      super(context, new_tags.downcase, tagger=nil)
    end
  end
  include HackTag
end