Simple controller override

products_controller_decorator.rb

Spree::Admin::ProductsController.class_eval do
  # don't try and load data before import action either
  before_filter :load_data, :except => [:index, :import]

  def import
    # do stuff
  end
end

routes.rb

Mystore2::Application.routes.draw do

  mount Spree::Core::Engine, :at => '/'

  Spree::Core::Engine.routes.prepend do
    namespace :admin do
      get '/products/import' => "products#import", :as => :products_import
    end
  end
  
end