My XML gallery needs next button

I have an xml galler which pulls my images in and sets them in coloumns of three what I need is a next button in my thumbnail movie clip which takes in the next set of images after 5 coloumns have loaded… “if that makes sense”

in my thumbnail mc I have this action script which loads my thumbs

images = new Array ();
xml_file = (“wheels/limited/images.xml”);
//xml_file = “images.xml”;
xmlload = new XML ();
xmlload.ignoreWhite = true;
xmlload.onLoad = function (ok) {
if (ok) {
count = this.firstChild.childNodes.length;
for (var i = 0; i < count; i++) {
curNode = this.firstChild.childNodes*;
images* = {caption:curNode.childNodes[0].firstChild.nodeValue, path:curNode.childNodes[1].firstChild.nodeValue};
}
boot ();
} else {
trace ("Could not load " + xml_file + “.”);
}
};
xmlload.load (xml_file);
// ------------------------------------------------------------
spacing = 2;
var columns = 3;
boot = function () {
for (var i = 0; i < images.length; i++) {
mc = container.attachMovie (“thumbMC”, “thumb” + i, i);
mc._x = (i%columns)* (80+spacing);
mc._y = Math.floor(i/columns)(80+spacing);
mc.path = “wheels/limited/thumbs/” + images
.path + “.jpg”;
mc.link = “wheels/limited/images/” + images*.path + “.jpg”;
mc.caption = images*.caption;
}
this._parent.picture._alpha = 0;
this._parent.caption._alpha = 0;
this._parent.picture.loadMovie (“wheels/limited/images/” + images[0].path + “.jpg”);
this._parent.caption.txt = images[0].caption;
setRollOver ();
};

any idears please