In the stock browser, I have not found a way. It can be done in most of the browsers available in the market though.
yeah, ive not been able to get about:debug or any of the about: variations to work in the fascinate browser to enable user agent. we may need to wait for a dev in a custom rom (like in the incredible) to do it. i love the browser in cm6 as it allows for desktop (which lets farmville run...for those who like that ) android, iphone and a few others.
That is one of the things I have always liked about the stock HTC browsers as well. You can set it act almost like any browser out there. I was a little frustrated when I tried to go to Bank Of America's full site and I couldn't on my SF.
