How can I change the user agent for the stock browser?

I am constantly annoyed by websites that force me into the (often terrible) mobile version of the site and provide no way to switch to the full version. I know Dolphin for example allows changing the user agent string of the browser to trick websites into delivering the full site, but I don't want to switch. Is there a way to do this with the stock browser? I'm open to hacks, and I have a Galaxy S Vibrant running 2.2 (Nero v5 with TouchWiz).