Mouse pointer to object AS change

I am having real trouble with an action script and cant seem to change the _xmouse and _ymouse founctions into _x and _y spesisic to another movie clip names dot maybe its just me but can anyone help me on this ive included the AS I am using bellow

onClipEvent (enterFrame) {
myRadians = Math.atan2 ( _root[COLOR=red][COLOR=black].[/COLOR]_ymouse[/COLOR]-this._y, _root[COLOR=red][COLOR=black].[/COLOR]_xmouse[/COLOR]-this._x );
myDegrees = Math.round ( ( myRadians*180/Math.PI ) );
_root.yChange = Math.round ( _root[COLOR=red][COLOR=black].[/COLOR]_ymouse[/COLOR]-this._y );
_root.xChange = Math.round ( _root[COLOR=red][COLOR=black].[/COLOR]_xmouse[/COLOR]-this._x );
_root.yMove = Math.round ( _root.yChange/20 );
_root.xMove = Math.round ( _root.xChange/20 );
this._y += _root.yMove;
this._x += _root.xMove;
this._rotation = myDegrees+90;
}