Ok, I downloaded this with the Portable Apps Suite, and its been working great.
It does this to all themes. It downloads them, then tries to install and says "Firefox could not install the file at 'https://addons.mozilla.org/en-US/firefox/ then the rest for the .jar file'
because: Unexpected installation error. Reveiw the Error Console log for more details. -203"
and i get this error in my error console: "e.location.getItemLocation(e.id) has no properties" in "file:///F:/PortableApps/FirefoxPortable/App/firefox/components/nsExtensionManager.js"
Update: It says error on line 4144 of that file, which says: "var e = validExtensions[i];" and it ties into the getItemLocation error on the next line.