A bit late here, but if the icons on this system were pasted on, instead of changed by the kaleidoscope control panel and extension (although it was actually an application), then to revert them to the original system icons you would need to cut them; copying them still would leave the pasted icon on the file, program, system item, folder or volume. Cutting the icon would allow the icon to show the original system icon the item had.
It would be a good idea to keep a copy of these icons somewhere, either by pasting them into the scrapbook in the apple menu, after which you could drag the copied icon onto the finder as a scrapbook icon clipping, or simply pasting the icons onto an unused folder or an empty text file.. you just never know when these icons may come in handy for someone.