[BigDan]

var startX:Number;
var startY:Number;
var endX:Number;
var endY:Number;
function start(){
 startX = 0;
 startY = 0;
 this.onEnterFrame = OEF();
}
function OEF(){
 endX = _x;
 endY = _y;
 ....
 moveTo(startX,startY);
 lineTo(endX,endY);
 startX = endX;
 startY = endY;
}