The track up Whakapounakau starts from the Outdoor Education Centre at Lake Okataina. The first part of the route follows the Western Okataina Walkway until you get to the top of the hill. The track to Whakapounakau turns off to the right and goes to the top which has and open clearing and a radio mast onthe top.
There are great views to the north and east from here looking over Lake Rotoiti to the sea and White Island in the distance.
Those numbers I have in my first post are the NZMG grid reference for both peaks.