rails helpers using outside of views

How to access helper methods outside of the view layer?

# models/category.rb
def description
  "This category has #{helpers.pluralize(products.count, 'product')}."
end

def helpers
  ActionController::Base.helpers
end

# products_controller.rb
def create
  @product = Product.new(params[:product])
  if @product.save
    flash[:notice] = "Successfully created #{@template.link_to('product', @product)}."
    redirect_to products_url
  else
    render :action => 'new'
  end
end

References

1. http://railscasts.com/episodes/132-helpers-outside-views