How do I change the feed URL of a element?

Suppose you have a gm:data element that gets vehicle snippets from Google Base like this:

<gm:data id="myData" data="www.google.com/base/feeds/snippets/-/vehicles"/>

You can use JavaScript to update the feed URL to show job snippets like this:

<script>google.mashups.getObjectById('myData').setData("www.google.com/base/feeds/attributes/-/jobs")</script>