End of Mexican Mountain Road, hike on the closed dirt road until you can make out a crossing of the San Rafael River and also a break in the cliffs to access the tower. You may find a a trail that partially formed with our passing that leads up a spur of talus slope through a number of steep steps. Take Care on this approach. Best way seems to be up to a the base of the North side of MM, then walk along the ridge to the north side of El Sombrero. To access the SE Corner, continue left around the to the backside or SE corner.