There's no way to have the co-pilot do all the actions in the checklists. While on the ground, before and after taxi it is the pilot's responsibility to perform most of the actions. This is how it is in the real world and that's what replicated in the sim. To "advance" the co-pilot through their actions or to confirm items in the checklists you use a keyboard or joystick button bound to CL650/checklist/check_item.