In every instance where an international, who is not a permanent residence holder, commences ANY employment in South Africa, a valid temporary residence permit with permission to take up employment is required.  This permit is issued either by the Department of Home Affairs or a South African Embassy or High Commission or Consulate.    This permits the international to conduct work and be remunerated for work done.
The Department of Home Affairs documentation is found below:

Internationals webpage

Last Modified: Mon, 08 Apr 2013 15:38:09 SAST