gistfile1.rb

def access_token
  @access_token ||= begin
                      twitter_request = session['twitter_request']
                      oauth.authorize_from_request(twitter_request.token, twitter_request.secret, params['oauth_verifier'])
                      oauth.access_token
                    end
end

def oauth(opts = {})
  @oauth ||= ::Twitter::OAuth.new(config.twitter_api_keys['token'], config.twitter_api_keys['secret'], opts)
end

def request_token
  @request_token ||= oauth(:sign_in => true).request_token(:oauth_callback => callback_url)
end

# Request auth from Twitter
session['twitter_request'] = request_token
redirect! request_token.authorize_url

# Twitter redirects back to callback_url with oauth_verifier from Twitter as param
user.token = access_token.token
user.secret = access_token.secret