1. A method for controlling a continuously variable transmission (CVT) of a powertrain system, the method comprising: determining a target clamping pressure and an actual clamping pressure for a clamping pulley of the CVT; determining a proportional term and an integral term based upon the target clamping pressure and the actual clamping pressure; determining, via a controller, an adapt correction term based upon the target clamping pressure and a CVT temperature; determining a commanded clamping pressure for the clamping pulley based upon the proportional term, the integral term and the adapt correction term; and controlling, via the controller, a pressure command to drive an actuator of a moveable sheave of the clamping pulley based upon the commanded clamping pressure.