To reach the McElmo Canyon trailhead, head south of Cortez on Highway 491. Turn right (west) on County Road G at the signs for the airport and/or Hovenweep National Monument. Go 12 miles on this paved road. Trailhead parking is an unimproved slickrock surface on the north (right) side of the road. No water, or other services are available.
Follow it to the junction with East Rock Creek then take a right. From there simply follow the loop counterclockwise back to this point and then retrace your steps on the first two trails to get back to the parking lot.
If you want a longer ride add the Sand Canyon Trail to the east and/or the Rock Creek Trail that loops west. The Rock Creek Trail (not East Rock Creek) is more technical. Sand Canyon is easier. These trails are rideable almost year round, but get hot in the summer.