If my understanding is correct, you are referring to the knee wall formed when you finished the attic. This is a pain in the butt to vent; join the club. I have a Cape Cod-style home which has the same issues. You need to vent the knee wall to the main attic above (the peak) while not losing the insulating properties for the rafter space in the sloped area. I used PVC pipes sparingly and insulated the knee wall facing the interior more.