Google Analytics plugin for umlaut characters åäö ü etc in IDN url?

I’ve got a wordpress installation on a IDN address (Internationalized domain name) with the letter ä in it (http://fiber.tärby.se/).

Currently Google Analytics only count visitors using Safari and Chrome, unless the visitors use punycode to enter the site
(fiber.xn--trby-loa.se).

To support IDN addresses (http://www.nätfångster.se or likewise) you would have to call .setDomainName(“fiber.xn--trby-loa.se”) in the javascript tracking code (using the punycode for the same url).
See the bottom of this page: http://productforums.google.com/forum/#!topic/analytics/uQkaviHUg3U

How do I add that kind of code to a wordpress plugin such as this “Google Analytics for WordPress”?

http://wordpress.org/extend/plugins/google-analytics-for-wordpress/