iTunesPauser is a simple application that when run will pause or resume iTunes. If iTunes isn't currently running, it will launch it. That's all.
The latest Microsoft IntelliType Pro keyboard drivers -- which infuriatingly don't support the Microsoft Office Keyboard fully -- have a media "Play / Pause" option which only seems to work with Windows Media Player. By altering the command to execute iTunesPauser, you can use the button to control iTunes.
You'll need the Microsoft .NET Framework Version 2.0 installed.
Unzip the downloaded file and put the two extracted files together somewhere. Run iTunesPauser.exe.