Yes. It's not a separate brake system. To set the parking brake, you hold the brake pedal and activate the parking brake system. That traps the hydraulic fluid that you were applying by holding the brakes so that the brakes will continue to be held when you release pressure on the toe brakes. The system has a hydraulic accumulator which aids in maintaining that pressure.

For a tow, you would run the APU to provide electrical power to run the electric hydraulic pumps to provide the hydraulic pressure for the brakes.

The move teams have their own checklists that they follow when moving or taxiing aircraft.