charmed, i've been there recently. accomplished what you want to do.
You definitely want to add that swf to the tpl_header.php file for your custom template.
may I suggest you use the swf object method. You will need to download swfobject.js ( javascript file) and you can find more about that here:
http://blog.deconcept.com/swfobject/
i think follow that link tothe latest, which is version 2.0
once you have these, format your javascript like this :
<script type="text/javascript" src="swfobject.js"></script>
<script type="text/javascript">
var flashvars = false;
var params = {
allowscriptaccess: "always"
};
var attributes = false;
swfobject.embedSWF("myFlashFile.swf", "showFlash", "200", "200", "8.0.0", "expressInstall.swf", flashvars, params, attributes);
swfobject.addParam("quality", "high");
swfobject.addParam("wmode", "transparent");
swfobject.write("flashcontent");
</script>
// and then on the template, you place the div tag to position your swf: //
<div class="thisMYFlash" id="showFlash" >
<div class="myStyleSheetReferenceHere" id="myStyleSheetReferenceHereID">
You need flash. if you have it, you'll see the flash. if not, you'll see my text here. go get it, install it!!!
</div>
</div>
and that should do it. swfobject is the best bet for easiest flash embedding...