I have the following DNN setup (6.2.5):

mydomain.com
portal1.mydomain.com
portal2.mydomain.com
...

I have Google Analytics (GA) hooked up to my root domain (mydomain.com), but I'd like to track all my subdomains with the same GA account.

GA has a simple solution for this scenario.

<script>
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-12345-1']);
_gaq.push(['_setDomainName', 'example-petstore.com']);
_gaq.push(['_trackPageview']);
</script>

How do I implement this with DNN's Google Analytics module?

URL Parameter textbox is my only hope, but I have no idea what to put in there to get this to work.