To wake up Roland's Spy, you need to ignite 3 Varkids at once. With a Fire Weapon that can take some work just because of the Varkids dying because of burn damage. If this is not working then head for Varkid Ranch and use one of the Incinerators there after luring a number of Varkids to you. He will introduce himself: Mordecai. He will recommend hijacking the train. To this end, Roland will direct the Vault Hunter to go meet Tina.