Hie Travel requirements

I need to confirm how I can handle my situation.I booked a flight from Wuhan to South Africa.So they have me a connection flight in Hong Kong.I have extra baggage which I paid from Hong Kong to South Africa.I don't have money to pay again from Wuhan to Hong Kong it's expensive.I am thinking of travelling to Hong Kong by bus and catch my flight there to South Africa.How do I go about it .What do I need to travel to Hong Kong.I have my exit visa and airticker with me.What else is required