If your cuttings have completely dried on the ends where they are cut to the point where they form a hard crust surface, then they are fine to root. This generally takes 1 to 2 weeks after cutting them. Once this occurs, they can be placed in totally dry soil. A few inches should do the trick.
In a week or two after this, uproot the cactus to check to see if it has rooted. It will mold if you put it in wet soil, so make sure it is dry. If it has rooted, and you see no mold, then it is ready for light watering. Just give it a little every once and a while. If you over-water, it will rot.
I've never had to use a rooting hormone for cacti.