If you are using swfobject 2.1 then you can do this...
read this here...
http://code.google.com/p/swfobject/wiki/api
look down at this section... swfobject.getQueryParamValue(paramStr)
you'd want to do this and pass the xml file info to the flash var "pano".
Or, if you had a default xml file that you wanted to use, you could pass the flash var specific to the image file(s) you wanted to load.
There might be other / better / different ways of doing this... but since swfobject is there, it's an option.