I took the liberty of updating pdurrant's applescript to run the new epubcheck-3.0b4. I don't know how to make anything but the simplest applescript but updating pdurrant's didn't seem too hard - at least I think I did it right. I tried it out on both an epub that validated and one that didn't and it seems to work. Thanks pdurrant for the original script.
epubcheck_3.app.zip