It's difficult and near impossible to ride in China but the official line from the embassy in Vietienne is that you need a Chinese tour operator to secure the visa for the trip, furnish a detailed plan of dates and places and have a fortune of good luck. I am working on it myself, among other difficult trips such as overland Mynmar and will post if I get any news on relief for riders. As for organized trips, try contacting Dan or Digby at
http://exploreindochina.com/, they may have a bit more information on it.
throttle wrist aches for everyone