Big Kangaroo is a fun little climb. From the hairpin just past Rainy pass, park, and then head up Early Winters Creek for about a half mile. Cross the creek (look for airplane wreckage) and then head up forest eventually hitting avalanche slopes. Head up (stick to treecover for easier going) and onto open slopes. Continue up loose scree. There will be some routefinding problems due to loss of perspective here. Head up the final gully, staying left until it narrows. Climb up to below chockstone.
We didn't rope up for the stretch from the chockstone to the ledges, where you can set up a belay at some blocks. From here, there is less than a pitch to go. Step across narrow section, and move around corner to ledge. Sling the flake as this will be your last real pro. Friction up to another ledge (horizontal crack might take a piece). Move right, friction up to crest and then follow crest to tiny summit. On the summit you'll find a very loose museum piece quarter inch bolt. The brave could rappel directly back to the belay from this bolt. The sane will just downclimb the thing, which we did.
This climb is a lot of hiking on pretty stressful loose crap for not much climbing. Most of the rock around here is slabby domes (where the rock is sound). The summits are all non-trivial to get off unless you enjoy downclimbing unprotected friction.