Hi, there isn't really any bouldering in or near joburg, your best option would be to drive the 2 and a half hours to waterval boven to climb routes - there are hundreds of awesome routes in a spectacular setting.
In Port Elizabeth there is bouldering and a few routes at lady's slipper, don't know the exact directions, sure someone on the forum can help.
Cape Town has plenty of bouldering in silvermine (the reserve on your left as you go over ou kaapse weg on the way down to cape point), rehill (above simonstown) and on table mountain above and below table mopuntain road. It also has plenty of routes, trad on table mountain and loads of sport crags further down the peninsular.
hope this helps