gistfile1.rb

# in config/initializers/navigatrix.rb

Navigatrix.register_item_renderer(:my_item) do
  def link
    link_to(name, path, class: "my-class")
  end

  def unlinked_content
    content_tag(:span, name)
  end
end

# in your code
render_navigation({"Home" => "/whatever"}, {item: :my_item})