Kindly note that you can now buy bus tickets from Johannesburg to Lusaka at Kerk Street and vice versa.
You will be required to submit your full details to the bus companies as per a template that has been given to them. Once the template is filled in full, the bus companies will submit the list to the Zambia High Commission.
The Zambia High Commission will facilitate authority for passage through Zimbabwe. Please note that the onus is on the bus companies to do the rest of the clearances required.
Those that are driving privately, you will need to go directly to the Zambia High Commission to make necessary arrangements to request for authority of passage through Zimbabwe.