Auto to Manual Pedal conversion

Pedal boxes arent easy to get my hands on here, a long way from Hamtramck...Im probably more interested in the mechanics of adding a clutch pedal to the existing auto pedal box if possible? Is this something that will work or will I be reinventing the wheel?
it works, all you need is the 4 speed brake and clutch pedal and shaft, I done it with the box still in the car and added spring if needed.