How to get there:
From Los Angeles, go north on I-5. Locate two consecutive exits, Exit 202, Gorman, followed by Exit 205, Frazier Mountain Park Road. These two exits are also connected by a parallel road running just west of I-5. Locate Gold Hill Road running south from this prallel road about 1.5 kilometer west of Gorman. Drive Gold Hill Road, first uphill, then across a shallow pass, then more gently downhill into a broad valley. The road gthen turns 90 degrees right and climbs across a second pass before finally descending into the valley at the base of Alamo Mountain. The road now climbs the side of Alamo, it is still paved, but now turns to a 4WD dirt road. After a long climbing ascent the road finally hits a signed intersection. From here, a dirt road circles the summit of Alamo. The summit can clearly be easily climbed from many points, the shortest approach may perhaps be on the far side. Drive around (going right is likely the shortest route). I parked at a small turnout at location N34.66558, W118.96870, elevation about 2100 meter.
From the trailhead described above, the route to the summit is an easy uphill walk. The only obstacle is fallen trees, quite many all over the route. Most of them can be crossed rather easily.
One should note that the big boulder at the location of the the map point with a spot elevation of 7367 feet is definitely not the highest point. Rather, the next hump (south-east) with a high point near its east side is highest. This is where the summit register has been placed.
After coming from Mount Pinos, I drove the short distance to I-5, then located Gold Hill Road. It took quite some time to drive this road, but finally I came to the signed road fork where the dirt road that circles the summit begins. I drove left and arrived at a suitablke spot to park at 1630. It took me 20 minutes to walk to the summit area. I first arrived at the hump marked on the map (and on Peakbagger!) as the highest. I quickly realized that this was incorrect and proceeded to the highest point. After about 15 minutes, I walked back down to my car, the descent took another 20 minutes.