No, you can't make a jacket potato in a wok. You can make a jacket potato in the microwave or in a real oven. You can make other potato dishes in a wok.
Another way to cook a jacket potato is wait t'il Nov 5th and bake it in embers of your bonfire. I am having one tonight. Pricked rolled in light fat, sprinkled in salt and baked in fan oven @200 for an hour. The filling will be home made chilli con carne sprinkled with Jalapa Nokia powder. Stand by for blast off.