Mt Irvine (4197m) and Mt McAdie (4206m) are located in the Mt Whitney area of the Eastern Sierra
The Meysan Lakes trail starts from the last Whitney campground before Whitney Portal (at about 2400 meters of elevation).
You have to park the car on the road and walk through the campground,
looking for the trailhead that is actually hidden among summer homes.
If you start hiking before sunrise, this is not trivial at all.
To make matters worse, the trail crosses the paved road one more time: walk
a bit uphill and look on your right for the second start of the trail.
Very long switchbacks (that will be very annoying on the way down) take you around the wall in front of you and into the valley created by the creek that comes down the lake. The trail ends at a meadow. Continue in the same direction (roughly south) and enter the lake from the west.
Mt Irvine is easily (class-2) climbed from the western side of the lake. There are several chutes that take you either straight to the summit or to the bowl between Mallory and Irvine.
Mt McAdie is reached via Arc Pass, which is next to Consultation Lake, but getting to Consultation Lake implies entering the Mt Whitney Zone and its terrifying bureaucracy. You can traverse from Mt Irvine to McAdie via Arc Pass but the ascent of McAdie's east face is not trivial. The ascent of the east face is easier. You can reach the east face either via Crabtree Pass (south of Arc Pass) or via Whitney Pass (southwest of Consultation Lake). If you have to get the permit for the Whitney Zone, you might as well hike Whitney Pass that takes you straight to the east face of Mt McAdie. McAdie has two summits and the northern one is obviously the higher of the two. Climb to the notch between the two summits and then work your way up to the northern summit. This is easier on the east face (the face facing Whitney, not Irvine).
Mt Mallory (4221m) is an easy detour from Mt Irvine.
From Mt McAdie you can descend to Consultation Lake and then cross over to the Meysan Lake trail via an unnamed pass.
If you do this, you'll be briefly in the ridiculous Whitney Zone, for which technically you need a permit (yes, even for day hikes).