How do you take the slack movement on back caliper on a mazda6 2003?

How do you take the slack movement on back caliper on a mazda6 2003?
the piston must be screwed (turned) in to bottom out to accept new brake pads this is due to the integrated park brake mechanism built into caliper. there is a special tool that screws piston it can be done with water pump (channel lock )plyrs dont damage dust seal once job is done pull and release park brake handle about 15 time to self adjust excess space between pads and rotors g if caliper has excessive paly in the mounting pins buy a rebuilt loaded caliper from auto parts store cheaper then dealer