For what it's worth, here's a quick-and-dirty option for consideration: rather than having one program watching the clipboard all the time, have several similar programs that each carry out one simple task and immediately exit. Then you link each to the desired keystrokes through Windows shortcuts (each being Ctrl-Alt-<letter>). This may well present some delay for each actuation depending on your hardware and load, but it should work and avoids having to filter through every keystroke in the system just in case it is meant for your application. This does work, but whether it will be responsive enough for your needs can only be answered by a test.
I'd like to be able to assign to an luser