В параметрах функции setInterval можно задать интервал появления картинок...

Код:
//вставим слайд
var totalElements:Number;
var arrayElements:Array;
var slideShowID:Number;
var picNum:Number = 0;
var target_mc:MovieClip = _root;
meXML = new XML();
meXML.ignoreWhite = true;
meXML.onLoad = function(success:Boolean){
if(success){
var rootNode:XMLNode = meXML.firstChild;
totalElements = rootNode.childNodes.length;
arrayElements = rootNode.childNodes;
nextPicture();
slideShowID = setInterval(_root, "nextPicture", 1000);
}
}
meXML.load("temp.xml");
function nextPicture() {
if(picNum < totalElements) {
var mcl:MovieClipLoader = new MovieClipLoader();
target_mc.image_mc.removeMovieClip();//удалим контейнер если таковой имеется в наличии.
target_mc.createEmptyMovieClip("image_mc",target_mc.getNextHighestDepth());
var secNode:XML = arrayElements[picNum];
var imagePath:String = secNode.attributes.loc;
//вводим изображение нежно)
var mclListener:Object = new Object();
mclListener.onLoadInit = function() {
resizePict(target_mc,target_mc.image_mc,20);
target_mc.image_mc._x = (target_mc._width - target_mc.image_mc._width)/2;
target_mc.image_mc._y = (target_mc._height - target_mc.image_mc._height)/2;
var imgTween:Object = new Tween(target_mc.image_mc,"_alpha",Back.easeOut,0,100,3,true);
target_mc.image_mc.filters = [shadowFilter()]; //тень на плетень
picNum++;
}
mcl.addListener(mclListener);
mcl.loadClip(imagePath,target_mc.image_mc);
} else {
clearInterval(slideShowID);
}
}