Kirupa tute worked great! Until

Hi,
I just used Kirupa’s tutorial, “Launching a Centered Pop-Up Window”
http://www.kirupa.com/developer/mx/centered_popup.htm
with great success.

It worked just like it was supposed to–in a test-page situation.

But when I tried to transfer it to my real-life situation, it refused to work.

My reality involves the test-page being called into a situation like this:
/*
_root.createEmptyMovieClip(“loadExternalSwiffs_mc”, 1);
loadExternalSwiffs_mc._x = 0;
loadExternalSwiffs_mc._y = 103;
_root.loadExternalSwiffs_mc.loadMovie(“introSplashPage.swf”)
*/

Only it’s even more complicated than that because the test-page isn’t that introSplashPage, it’s one (called "aaronCreditsList.swf) that’s being loaded into that level from a button inside the root document, like this:
/*
on (release) {
_root.loadExternalSwiffs_mc.loadMovie(“aaronCreditsList.swf”)
gotoAndStop(“collapsed2”);
gotoAndStop(“collapsed”);
}
*/

I guess what I need to know is where–now–to put this Kirupa copy:
/*
_root.openWinCentre = function (url, winName, w, h, toolbar, location, directories, status, menubar, scrollbars, resizable) {

getURL ("javascript:var myWin; if(!myWin || myWin.closed){myWin = window.open('" + url + "','" + winName + "','" + "width=" + w + ",height=" + h + ",toolbar=" + toolbar + ",location=" + location + ",directories=" + directories + ",status=" + status + ",menubar=" + menubar + ",scrollbars=" + scrollbars + ",resizable=" + resizable + ",top='+((screen.height/2)-(" + h/2 + "))+',left='+((screen.width/2)-(" + w/2 + "))+'" + "')}else{myWin.focus();};void(0);");

}
*/

And/or how to modify it slightly so that it can “find” its way to Kirupa’s button copy:
/* on (release) {

//customize the window that gets opened
// 0 equals NO.
// 1 equals YES.
address = "aaronCreditsActor.html";
target_winName = "mainWindow";
width = 700;
height = 350;
toolbar = 0;
location = 0;
directories = 0;
status = 0;
menubar = 0;
scrollbars = 1;
resizable = 0;
//sends data back to the function
openWinCentre(address, target_winName, width, height, toolbar, location, directories, status, menubar, scrollbars, resizable);

}

*/

I’ve tried a bunch of things but, so far, nothing has worked.

TIA