1) Cut them into eighths lengthwise.
2) Toss with whatever seasoning you prefer - I typically do some olive oil, sea salt, cinnamon
3) Put them on a shallow roasting pan or tray with an edge.
4) Set oven to broil - typically ~450
5) They cook in 20-30min - at 15min I typically pull them out and test the center of the largest one with a fork, if its soft then all are good to go. You can do as many potatoes at once this way and not have to adjust the cook time much - just gotta flip them all around a bit.
I cook them this way all the time... it just takes too long any other way.
Advice:
If you do a whole potato, microwave it for about 2min then bake/grill - the microwave will soften it up enough in the center and will drastically cut down cooking time.
If you wrap in foil, expect baking/grilling to take well over 45min - aluminum heats up to only a certain level so it ends up creating almost a miniature oven within the oven and gradually heats the potato and traps in moisture. This results in a softer, moister potato, but too damn long to cook IMO.