Sounds like a fun trip!
You can follow the broad sandy SW ridge of Mount Langley to the saddle that lies just short of Major General. The chute that descends west from there is class 2. The scree is loose but not too difficult. On the map that Steve linked to, you can see a small tributary stream to Rock Creek below where that is. From around that stream you can begin to head north toward Sky Blue Lake.
This route on Mount Langley is described by Secor as "West Face”, but beware. As you follow the SW ridge down from the summit, be careful not to descend to the west before you reach the saddle. Viewed from Miter Basin, the rest of that west slope of Mount Langley looks quite a bit more treacherous than class 2.
