Take the graded track to Sylvestors Lookout. A well used taped trail is followed up to a knoll 397 053 and then east to the top of Laidley falls. Find the route down the west side of the falls and then walk under the falls contouring along the base of the cliffs to hole in the wall. (I have known other walkers to descend too far around here). Soon after the hole in the wall the ridge top is attained and followed over Boar's Head and then up towards Mt Castle.
When the cliff on the south of Mt Castle is reached, contour around the west side without dropping until the cliff is passed and Mt Castle is ascended. Older descriptions describe a road but it has long disappeared with land slips and vegetation regrowth. There are several good campsites on Mt Castle and if not in drought water can be found at the top of the ampitheatre of cliffs on the north side of the mountain (just don't count on it).
The route to Kangaroo Mountain can be found by reaching the point at the top of the cliffs 414076 and carefully picking the route down. From memory it is better to start to veer to the north west a bit.