The inputs on the Chimp are setup as high impedence inputs; whether you directly connect a low or high voltage, it wont hurt anything on the chimp until you start getting way over 5 volts.
Maybe I’m missing something, but I just dont see how that would or should work. The button labelled ‘X’ has the cathode end of a diode on one side, and +V on the other; regardless of whether the button is pressed or not, no current will flow through there; it certainly won’t trigger anything. Yikes. More I look at it, the more I don’t have a clue whats supposed to go on in that circuit.
From your earlier description, you said the 555 should be setup in a monostable configuration, with the RC calculated to be 0.03 seconds, roughly two frames. That all sounds good. The timing signal from the 555 should be easy to use with the rest of the circuit. But I dont understand the need for the diode in the configuration. You should end up wiring the 555 section like this:
File:555 Monostable.svg - Wikipedia, the free encyclopedia
Now for the activating button. If Im remembering/assuming right, this will be a standalone button, not connected directly to anything except your kara button. If that’s the case, you need to wire a resistor that is somewhere between 4.7k ohm and 10k ohm so that one leg connects to Vcc, and the other to the Trigger line (pin 3 of the 555). Connect the trigger line to one leg of your kara button, and the other leg of the button to ground. You now have a button that will trigger the 555.
From there, it should be easy to figure out how to wire a couple of gates, or maybe just diodes, to the buttons that are being controlled. You never mentioned which combination of buttons you’re using for the kara; whether its a separate button (Roundhouse~Throw) or one of the same buttons (Short~Throw), or any details how exactly the kara is to be done. Flesh that out quite a bit in good detail before going any further. Does the first button need to be held? Need to be released before the throw?