I started from the Smithbrook Trail #1590 off of NFS Road #6700 which is just east of Steven's Pass on Hwy 2.
The trail goes up 1 mile to a junction with the Pacific Crest Trail. Turn left (Southbound) onto the PCT, continue about 2 miles and turn left down the Lake Valhalla access trail.
Travel along the west shore of the lake on an unmaintained and overgrown trail. Continue across the boulders at the south end where there are a couple small campsites. Cross the small outflow creek and from here, travel south cross-country heading for the saddle on the ridge. I angled up, staying high where I could see to pick spots to cross the boulder fields and brushy areas. Some guides say to just travel south to the gully (as seen on the right in this picture) and just follow it up.
Once on the ridge, enjoy a nice view of Lichtenwasser Lake on the other side, then turn left for a short climb to the top. The west summit which overlooks Valhalla looks awsome, but is a scramble I didn't attempt. This picture shows nearby Mount McCausland W7W/SN-074 to the right.
The east (true) summit has plenty of room in the activation zone along with a few trees and rocks to sit on.
It's probably an hour and a half trip to the top from the campsites - YMMV. I really enjoyed going up while it was shady in the morning..