Maybe you can adapt this...
Code:
var num = 0;
var sideNavListener:Object = new Object();
var sideNavLoader:MovieClipLoader = new MovieClipLoader();
sideNavLoader.addListener(sideNavListener);
sideNavListener.onLoadInit = goPage;

var contentListener:Object = new Object();
var contentLoader:MovieClipLoader = new MovieClipLoader();
contentLoader.addListener(contentListener);
contentListener.onLoadInit = prepBtns;
contentLoader.loadClip("btns.swf",content_mc);

function prepBtns(mc:MovieClip) {
        mc.button1_btn.onPress = loadMenu;
        mc.button2_btn.onPress = loadMenu;
        mc.button3_btn.onPress = loadMenu;
        mc.button4_btn.onPress = loadMenu;
        mc.button5_btn.onPress = loadMenu;
        mc.button6_btn.onPress = loadMenu;
}
function loadMenu() {
        num = this._name.charAt(6);
        sideNavLoader.loadClip("menu.swf",sideNav_mc);
}
function goPage(mc:MovieClip) {
        mc.gotoAndStop(num);
}