Jon,
CANPAS don't need to know about an alternate. If you use Irving for your FBO they are at both St Johns and Banger, just call them on VHF if you divert and they will call CANPAS for you and get the officers to cancel at Banger and meet you at St Johns. They are very helpful. You may have to wait for the Officers to get there from the main terminal or in town depends where they are.