Don't know if this'll help or not, but with most cruise controls I've seen, the only real mechanical difference is that where automatic trans units have one cruise shut off switch attached to the brake pedal, the manual trans cruise controls have the brake pedal switch and a second shut off switch attached to the clutch pedal.
Just like when you want the cruise to shut off when you hit the brakes, you also want the cruise to shut off when you hit the clutch.