If you want to regulate the spin by the throttle, you should probably doing something like this:
Code:
if (joyStick->GetRawButton(4))
joanRobo->HolonomicDrive(0.0, 0.0, -joyStick->GetThrottle());
//Turn right
else if (joyStick->GetRawButton(5))
joanRobo->HolonomicDrive(0.0, 0.0, joyStick->GetThrottle());
//Regular holonomic movement
else
joanRobo->HolonomicDrive(joyStick->GetMagnitude(), joyStick->GetDirectionDegrees(), 0.0);