I don't know anything about your game. To start with though:
what is inside your arcade pedals? is it a POT based thing? is it just a button that gets mashed down (like..you're either going or not, not going half speed by holding the pedal half way down) or is it optical?
I don't think there's a 3rd option. after you know that, you need to know what's in your Mad Catz controllers.
I just went through interfacing an optical interface (Steering Wheel) and a POT (pedal) in a dedicated Road Blasters I mamed.
maybe someone else wants to look up what you've got, or already knows. but i'm pretty lazy.