How to send user input into another (terminal server) session?

Windows API has functions that simulate user input, such as keybd_event, mouse_event and SendInput. However they do this on the input queue of t开发者_Python百科he current session.

I'd like to be able to send user input from a process running in session 0 to any other session. One way to achieve this is to run an agent in every session that will do the work. However I'd like to do this without injecting agents if possible.

kernel-mode solution is also ok. Thanks in advance.