This route is a direct and relatively painless way to summit Mary Austin from Little Onion Valley in the spring.
Park at the gated dirt road around 7000' on the road to Onion Valley, where it turns at its northernmost point. Follow the dirt road for a bit over a mile, until it ends at an interesting collection of old mining junk, including a bulldozer and a large engine. Continue cross-country up Little Onion Valley, staying on one side or the other of the terrible brush near the stream. The left (south) side had minimal brush in June 2009. Continue past the first, broad gully leading to Mary Austin, then cross over to the north side below 10,000', where a narrow chute with trees above its lefthand side becomes visible.
Climb the narrow chute starting at around 10,000' (pictured above) until it opens up. Head up the lefthand side of the face to avoid the worst of the loose rock, then continue along the ridge to the summit.
Crampons, ice axe.