Just drop the whole idea altogether. You don't want an HDTV as a monitor for 5 reasons:
1. They're more expensive than their monitor equivalents.
2. They're absolutely plagued by overscan issues.
3. The vast majority cannot run their native resolution with a computer. For example, with a 720p TV you'll end up getting a 1280x720p image scaled over a 1360x768 resolution, making everything blurry.
4. Color representation looks like crap since they're optimized for television use.
5. Low resolutions shouldn't be spread over large displays for computer use, it looks really bad. (this doesn't apply to your situation exactly if it's a 1080p TV, but it's good to know)