If you'd walk him in a leash a couple of times, he would soon know his way around good enough to find his way "home" to you if let out by himself. You might have to feed him good for a month or so first though, so that he sees it wortwhile to return... I don't know, do you think he has been a housecat before?
My cat is outside (on his own), regardless of season, about 20 - 50% of each day. Always comes back and waits for the door to be opened to be let in, eat, sleep and just lay around being lazy
Edit: Then of course, he is what you would call a tame cat. But I guess yours is too, if he accepts being indoors.