You can't hook the TClock application to the system tray because you're probably running an unsupported version of the Windows operating system. According to the developer's page, the application is compatible with the following versions of the Windows operating system: 95, 98, Me, NT4.0, 2000 and XP.
I have tried to run the TClock application on my Windows 7 Ultimate x64 OS and it doesn't even want to start. I have also applied all the compatibility tweaks that were available and still nothing.
To find more about the software, access the official website: http://homepage1.nifty.com/kazubon/tclocklight/index.html