For the Slide Show Viewer Firefox Extension to work with K-Meleon 74.0 and K-Meleon 75.0 Beta, download Slide Show Viewer
https://addons.cdn.mozilla.net/user-media/addons/296642/slide_show_viewer-1.2.0-fx.xpi and rename it to
ssViewer@mozilla.org.xpi
Next copy
ssViewer@mozilla.org.xpi into the extensiosn folder.
Then download Slide Show Viewer
http://kmext.sourceforge.net/extensions/lssviewer.7z from K-Mwleon Extensions Central
Last extract macros from Slide Show Viewer
http://kmext.sourceforge.net/extensions/lssviewer.7z into the K-Meleon Root Folder.