The method is very easy, just copy either the bottom or top application file depending on where your taskbar is oriented.
This is what SweatyFish says:
” Made a simple app to add a drop shadow to your taskbar. One .exe for a taskbar on the bottom, and one for the taskbar on top. Use whichever you need…
No installation, just copy to your %Program Files% folder. And run whichever .exe you need.
-Adjustable opacity (darkness)
-Option to run at startup
Other than the ability to right click the shadow, it is non intrusive and doesn’t show anything in the system tray.
Right click the shadow to choose preferences or to close it.