Heres the thing: R1, R2, triangle, square, circle, and X buttons share the COM2. There are pulses for each of these buttons timed at a certain frequency. When these pulses occur, the voltage goes from 2.7V down to roughly 1.3V when the buttons are not pressed. When they are pressed, the voltage goes lower.
Now, if the PIC is monitoring these pulses on the COM2 line, it will not see the digital threshold for a low until the button is pressed far enough. But the PIC would also have to know which button is pressed so it does not register the button presses for the other buttons. That is the kicker.
On top of that, most people use a transistor to simulate a button press. When you do rapidfire 'on the trigger', you need to force the line on that button back to released voltage state. Well, the released voltage state is right in the middle (1.3V) of what the output voltage levels are for the PIC.
If you dont care about the other buttons being affected, then a simple RF on R1 is not very hard, but makes all other buttons useless.
I can show more when my DSO arrives tomorrow.