Chineese Group Visa for visit to Tibet

Sir,
We are 3 Indian Nationals plan to visit Lhasa and Everest Base Camp with our self driven vehicle from India.As per our Chineese operator who are going to organise our travel plan ,we need to obtain Chinese Group one from Kathmandu. Please advise the process to obtain such Chinese group Visa from Kathmandu for us. Also please inform whether we need further Chinese ones from India if we are granted such group one to enter Tibet.
Expecting your advise soon.
Your truly,
Sumit Batabyal
email:sumbyalgmail.com