Vertical thumbnail grid

Im sure there is a tutorial or reference thread as to how to make this scroller verticle as opposed to horizontal, but i can not find it.

Any reference or pointers would be greatly appreciated.

The snippet below is from a tutroial (adding thumbnails) from kirupa.com

function thumbNailScroller() {
// thumbnail code!
this.createEmptyMovieClip(“tscroller”, 1000);
scroll_speed = 10;
tscroller.onEnterFrame = function() {
if ((_root._ymouse>=thumbnail_mc._y) && (_root._ymouse<=thumbnail_mc._y+thumbnail_mc._height)) {
if ((_root._xmouse>=(hit_right._x-40)) && (thumbnail_mc.hitTest(hit_right))) {
thumbnail_mc._x -= scroll_speed;
} else if ((_root._xmouse<=(hit_left._x+40)) && (thumbnail_mc.hitTest(hit_left))) {
thumbnail_mc._x += scroll_speed;
}
} else {
delete tscroller.onEnterFrame;
}
};
}
Thank you.