The flat set and scent post set are very similar. They do not require digging a hole and the trap is bedded in loose dirt. The attractant is usually some type of urine and may incorporate some type of visual attractant such as a bone or piece of scat. It is a productive set because it mimics a natural territorial marker that all canines leave. They find a prominent object such as a post or rock and urinate on it to mark their territory.
To construct the set, find a prominent post or rock, and bed a leghold trap in front of it. Then you simply add urine to the object, and you may incorporate scratches in the dirt to simulate a coyote scratching its hind legs after they have urinated on the object. You may also use no urine and just use an object that coyotes will investigate naturally such as a bone.