Very difficult. The Chinese were... proud to say the least, and as such they never would have wanted to play second fiddle in a communist empire. The Russians would have needed something to keep them from being able to break away, rather than coercing them to stick around.
-The Soviets merge Meingjiang and Manchukuo into an independent People's Republic of Manchuria. With just Manchuria bordering Korea, the communists are kicked out of the north because Mao doesn't have to worry about Americans on his border.
-Annex the two Independent East Turkestan republics in western China as the East Turkestan SFSR
-Covertly support an independent Tibet that would be pro-Soviet, even if under Dali Llama leadership. He today is a self proclaimed Marxist so it could work.
-Have the RoC keep Hainan and the Leizhou peninsula with Kwang-Chou-Wan
The middle Kingdom would end up in the middle of Western allies (Japan, Korea, RoC) and the Soviet Union and its puppets (Mongolia, East Turkestan, Manchuria, and Tibet)
You end up with an incredibly insecure China that is surrounded by Soviet troops and allies on almost all sides, and American troops and allies on the other. While America can hit the coasts and blockade China, Russia can just steamroll through it. Soviet puppet Manchuria would be the only thing keeping American troops in Korea from marching into China, and the Soviets can storm into China from the mountains of Tibet or through the plains of Manchuria.