Thanks, JohnHell. I knew it had to do with the toolbars.cfg file, but wasn't really sure where that file was. I copied the setting and the BMP file from the KM-16-F3628 skins folder on another drive, and now the toolbar button is in place.
Isn't K-Meleon just wonderful, in the way you can change its appearance and configuration simply by adding some script to an already existing config file? It