Shoutbox

can someone change this code so instead of it popping up like a popup but have to click something 1st?

code:

---

<SCRIPT>
function showShoutbox() {
    var x=-30;
    var y=-60;
    if (document.layers) {
        x=x+(window.outerWidth-200)/2;
        y=y+(window.outerHeight-300)/2;
    } else {
        x=x+(screen.Width-200)/2;
        y=y+(screen.Height-300)/2;
    }
    if (x<0) x=0;
    if (y<0) y=0;
    var w=window.open("http://284628.myshoutbox.com/","shoutbox","top="+y+",left="+x+",width=200,height=300,location=0,menubar=0,toolbar=0,status=0,resizable=0,scrollbars=1");
    w.focus();
    return;
}
window.onload=new Function("showShoutbox()");
//-->
</SCRIPT>

---