As promised, I have made the source code for both the Display Off tile and its installer available for download. displayOffTileSrc.zip (VS08 project) contains the code for the tile executable itself. It's nothing magic, simply creates a hidden window and sends a message to it to shut the monitor off. Dead easy to back-port project to Visual Studio 2005.
displayOffTileInstallerSrc.zip (VS05 project) contains the WiX project and code that creates the MSI used to install and configure the tile. Pay particular attention to the areas that detect existing OEM tiles. I strongly recommend you should leave that logic intact.