I stumbled on this email thread on starting Xmonad in Fedora 10. In anticipation of Gnome 2.24 being installable from Debian Experimental I dropped the following into
[Desktop Entry] Type=Application Encoding=UTF-8 Name=Xmonad Exec=xmonad NoDisplay=true X-GNOME-WMName=Xmonad X-GNOME-Autostart-Phase=WindowManager X-GNOME-Provides=windowmanager X-GNOME-Autostart-Notify=true
and modified the GConf key
/desktop/gnome/applications/window_manager/current to hold the value
/usr/bin/xmonad. Last but not least I removed my
~/.gnomerc. Log out, log in. Enjoy!
Yes, this is mentioned on the Xmonad wiki, though with slightly less details. I’ll hold off updating the page until I have Gnome 2.24 on my desktop.