The last time China sent army into another country obviously is during Korean War. During vietnam war, China also sent army personal into vietnam war as well, but not as many regulars as Korean war since U.S. did not dare to move into north vietnam for a full scale war after China issued her stern warnings.
The reason China did not send as many army soldiers into vietnam as korean wars is that China then also offered stern warning against U.S. not sending bombers into north vietnam, otherwise, China would do the same as what she has done in Korea. U.S. thus did not and north vietnam kept most of military facilities close to China borders for safety.
As for this time, China will just do the same by sending better weaponry into Pakistan. It is still the conflict between Pakistan and U.S. and NATO. China's involvement has to be asked by Pakistan government even though we have a close relationship. We cannot just send army or air force into Pakistan. It will be a violation of Pakistan's sovereignty if we do so without being asked. Even during Korean war, it is the elder kim who begged soviet for help and then kim and soviet begged China to help. I do believe the military hardware support or transfer is already on the way. How fast, how much are all depending on how the issue is resolved.
You have to tell the different levels of warnings issued by China. Our final warnings are indeed deadly. We issued our stern warnings before Korean war, before 1962 China-india border war, before the ChinaSoviet border conflict, before China-vietnam war and etc.
If you read those final warnings before those wars and conflicts China has directly involved, you should have already seen a pattern. Of course, you can ignore the pattern and think China is just pretending to help.
If you say China is just too weak to help or did not dare to help since the enemy is just too strong, well, China fought the so-called U.S.-led U.N. armies with nuclear weapons during Korean war. China also fought then u.s.s.r that has hundreds of times more nuclear weapons and more than one million division soldiers along china-soviet/mongolia borders. If we were not afraid then, why should we become afraid when we are indeed much more stronger than we were in the past, and have much more retaliatory weapons in our disposal than the past??? We have almost none of such retaliatory weapons in the past during those wars, don't we?
Well, you can still believe the world is flat and there is nothing I can do about it.