Thanks for the info, guys.
I specifically bought a big-screen, regular CRT TV for playing lightgun games (35" Sony). I have 2 PS2s (one with a DRE), but I do not have 2 TV's to use (one is an old 20" with no brightness control, and is too dark).
An inline/controller hack would be nice if possible. Referring to my old "diagram", couldn't the foot pedal be wired to a controller's button(s) in between the gun and the PS2?
Thanks.