The most straight forward route is via the Slab Route, for which directions can be found in Ernst Lotz book Jonkershoek and its Mountains. Follow this route until you reach the water shed deviding Jonkershoek and Banghoekvallei. Climb the small little pinacle. The cache is under some rocks one step lower than the top.
From the Slab route you can either ascend Thrid Ridge Peak, Virgin Peaks or push really far to the Twins. If you are lucky and early you may stumble accross someone attempting the Jonkershoek Marathon. If you do, spare a thought for them as they still have at least 7 hours of unmarked mountainous terrain to negotiate.