rails 2.3.5, Activerecord-sessionstore takes session-id from get-vars if passed by shockwave flash (uploadify) using rack-middleware

enviroment.rb

# part of config/enviroment.rb
...
Rails::Initializer.run do |config|
  
  # Load model files from sub folders
  config.load_paths += Dir["#{RAILS_ROOT}/app/models/*"].find_all { |f| File.stat(f).directory? }

  # Load middleware - initially used by flash-session-hack
  config.load_paths << "#{RAILS_ROOT}/app/middleware"

....

flash_session_cookie_middleware.rb

# this file should sit at app/middleware/flash_session_cookie_middleware.rb
require 'rack/utils'

class FlashSessionCookieMiddleware
  def initialize(app, session_key = '_session_id')
    @app = app
    @session_key = session_key
  end

  def call(env)
    if env['HTTP_USER_AGENT'] =~ /^(Adobe|Shockwave) Flash/
      params = Rack::Request.new(env).params
      unless params[@session_key].nil?
				env['HTTP_COOKIE'] = "#{@session_key}=#{params[@session_key]}".freeze
      end
    end
		
    @app.call(env)
  end
end

flash_session_middleware.rb

# this file should sit at config/initializers/flash_session_middleware.rb

ActionController::Dispatcher.middleware.insert_before(
  ActiveRecord::SessionStore,
  FlashSessionCookieMiddleware,
  ActionController::Base.session_options[:session_key]
)

How can I use that middleware for Rails 3?