Take Highway 1 South and turn left at the FOURTH traffic light where it dead ends at Linda Mar Blvd. (Highway 1 is closed here because Devil's Slide slid...)
Drive all the way up Linda Mar Blvd. until it dead ends.
Turn right. The entrance will instantly appear.
Note: There is a $5 entrance fee per vehicle. I recommend what we locals do -- park outside the entrance and do the 5 minute walk in ($1/minute -- not a bad idea for us possibly unemployed soon types).