On a second thought, I think you can use the following javascript code as temporary workaround.
Put this code between album tags:
In addition, put this code inside <head> tag of your HTML:Code:<script language=javascript><!-- calcsize(<!--[volume]--><!--[track]--> <!--[tracksize/]-->+<!--[/track]--><!--[/volume]-->0); //--></script>
It worked for meCode:<script language=javascript><!-- function calcsize(size){ document.write((size/1048576).toPrecision(4)+' MB'); } //--></script>