Infinite menu

Hey everyone i have this infinite menu that works great just like in the tutorial I was wondering if it was possible to alter the code so that when you rolloff the menu eases to a stop instead of abruptly stopping would that be a pain to do?

onClipEvent (load) {
xcenter = 480;
speed = 1/10;
}
onClipEvent (enterFrame) {
if (this.hitTest(_root._xmouse, _root._ymouse, true)) {
var distance = _root._xmouse-xcenter;
_x += (distance*speed);
_x>0 ? _x=-697 : _x<-697 ? _x=0 : null;
}
}

Any help would be great.
Thanks,
Chris