From the North:
Take I-5 south to San Clemente, and exit at Camino Estrella. Turn right, and take it to where it dead-ends at Camino Capistrano. Turn left, and go a mile to Monte Vista. Turn right, and look for the yellow-and-black "M" sign on the right.
From the South:
Take I-5 north to San Clemente, and exit at Avenida Pico. Turn left, and take it to where it ends at El Camino Real. Turn right, and go a mile to Camino Capistrano. Turn right, and go a fifth of a mile (second left) to Monte Vista. Turn left, and look for the yellow-and-black "M" sign on the right.
Map:
Click here for a map.