Regulations to get through china with a foreign plate

Hello there,
I've lately been wondering if it is allowed to drive a motorbike with Vietnam plate through China. I went to the Chinese embassy and they told me that through travel agencies you can get a permit to drive a vehicle through China.
But at the same time online I read it's impossible.
How does it work?? How did you guys manage to get in with a foreign plate?
Thanks a lot for the help!!

You work with a local agency and then you get to tour the country with an escort. It's very expensive.