Navigate from your starting point to MSB with Yahoo! Maps. This trailhead is about 4 miles south on Highway 1 from the Linda Mar Blvd. turnoff for the San Pedro Valley County Park approach. On the west side of Highway 1, look for an odd building "balanced" on some eroded sandstone. You cannot miss this! About 1/4 mile south of this, you will see a large dirt parking area on the east side of the road. Park here and start up the trail.
If you are without a car, or planning to do a through-hike which begins or ends at another trailhead, public transportation options are quite convenient. The San Mateo County Transit Authority offers bus service to the town of Montara, about one mile from the trailhead. On this schedule map, you would get off the bus at stop "B" in Montara, and head north along highway 1 until you reach the trailhead. A bus map from transitinfo.org
From the parking area, the trail contours along this gorgeous coastal hillside, climbing gradually to some benches and 180° views of the coastline. Vegetation is sparse; either coastal scrub or clean, grassy, windswept slopes. After 0.75 miles and 250 feet of climbing, you come to an obvious junction. Refer to the trail map given above. The yellow trail climbs straight up the hill, while a nearby paved road (red) provides a more steady climb up the slopes. The red trail is a mile longer, with some up-and-down, though its gentler grade makes it the preferred bicycle ascent route.
Both trail options meet on a high ridge. At this point, vegetation has turned to thick coastal scrub. Continue up the main Montara Mountain Access Road for a steep 0.9 mile/600-foot climb. Here you reach the junction (small sign) with the trails coming up from SPVCP. From here, simply follow the Montara Mountain Access Road another 1.6 miles/+600 feet to the north (true) summit of Montara Mountain.
Furthermore, there is very little usable water on any of the Montara Mountain trails at any time of the year, especially in summer. The hikes are short, but you should be self-sufficient.
Compared to the SPVCP approach, the MSB approach is more exposed to the wind and has less water.