Sounds like you should play around with Multibox further then. I really have no experience with it so I will have to leave that to others to help you with. It seems like a fairly robust program from what I have read. Perhaps synergy with keyboard broadcasting will work for you? I think (?) there is a way to turn off individual keys? Have not poked around with that either, I prefer the hardware route. Far more robust but far more expensive and less flexible - but damn if it doesn't work when I need it to.