ActionScript 3.0 :: Slow Continuous Side Scrolling Gallery

I'm trying to create the look at the following website: [URL]. Once it's loaded click the screen and at the bottom left go to portfolios. Click on one of them and you'll see a slow continuous side scrolling gallery. I've got everything working apart from when I mouse off it continues at the speed at which I left it. I would like it to slow to a default speed and continue scrolling as in the example I've given.

I should mention I followed tutorial here: [URL]. It's been a while since I dabbled with Flash and especially AS3! Here is the code I'm using so far.
Code:
import gs.*;
var centerX:Number = stage.stageWidth / 2;
var galleryWidth:Number = images.width;
var speed:Number = 0;
addEventListener(Event.ENTER_FRAME, move);
function move(e:Event):void {
[Code] .....