The source code for "Tracking an external link as a goal" is at the url below.
http://www.google.com/support/analytics/bin/answer.py?hl=en&answer=72712


Here's the code snippet utilizing javascript...onClick="javascript: pageTracker._trackPageview("/G1/example.com") This snippet is supposedly only used with older GA non-asynchronous code? Lets see. This test was setup at 7:00am on Saturday Dec 4, 2010. I have setup a goal in GA with "/G1/example.com" as the Goal.... no funnel. The standard GA tracking code is inside the /head tags. I chose "Head Match" in GA Goals.

Here's the test link to example.com:
test link to example.com