Almost, but if you are trying to understand the benifits vs cost of the systems, it replaces a bit more than the throttle cable and it puts the ECM in feed forward control rather than reaction control.
It replaces the entire cruise control system and actuator. It replaces throttle body dashpot to keep the throttle from closing too fast, and the idle air bypass system.
The signal from the pedal to the ECM is indeed analog and aredirect inputs. Two of them for redundant control. The ECM controls the throttle body actuator directly via a pulse width modulated signal and a feedback sensor. There are no outboard signal converters.