ActionScript 3.0 :: Stage Size Background Controlled By Accelerometer

I'm working on an application in Flash CS5.5. I've been working with the code snippets, and the template that deals with keeping an accelerometer-controlled movieclip on stage. That works great. However, I'm trying to find a solution having a larger than the stage sized background be controlled by the accelerometer, but stop moving once it reaches the edges of the movieclip. So, it would move all the way to the right until the edge of the movieclip, then stop. Below is the code sample that I've been trying to manipulate (from the included template that keeps the ball movieclip from going off-stage).

import flash.events.Event;
var accelX:Number;
var accelY:Number; 
var fl_Accelerometer:Accelerometer = new Accelerometer();
fl_Accelerometer.addEventListener(AccelerometerEvent.UPDATE, fl_AccelerometerUpdateHandler);
function fl_AccelerometerUpdateHandler(event:AccelerometerEvent):void {
[Code] .....