What is the equivalent alpha code to setRGB

1

What is the equivalent alpha code to setRGB?
thanx for any help.

Ps Im trying to change this code so it contorls the alpha of a movie clip instance name circle
the code is bellow:

onClipEvent(enterFrame){
	_parent.alpha = (_parent.RedSlider.RedControlBar._y+122).toString(16);
	if (length(_parent.alpha) == 1)
		_parent.alpha = "0" + _parent.alpha;
	//_parent.greenRGB = (_parent.GreenSlider.GreenControlBar._y+122).toString(16);
	//if (length(_parent.greenRGB) == 1)
		//_parent.greenRGB = "0" + _parent.greenRGB;
	//_parent.blueRGB = (_parent.BlueSlider.BlueControlBar._y+122).toString(16);
		//if (length(_parent.blueRGB) == 1)
		//_parent.blueRGB = "0" + _parent.blueRGB;
	finalColor =  "0x" + _parent.alpha; //+ _parent.greenRGB + _parent.blueRGB;
	_parent.circleColor.setRGB(finalColor);
	_parent.circleColor.setRGB(finalColor);
}