How to use:
For .ico – put icon to any folder, right click on desktop shortcut > properties > change icon > browse..

For .png – use Objectdock – in C:\Program Files\Stardock\ObjectDock create any folder, put icons to this folder, put your desktop shortcut to objectdock, rightclick on this shortcut: “Dock Entry Properties…” -> “Change image” > “Browse…” and find icon.