My keyboard have physically the bépo layout http://bepo.fr/wiki/Accueil I can force the use of this layout during the first phase of the installation via the kde system settings (after choosing an incorrect layout during the installation process), but after the first reboot, I have great difficulty to type my passphrase to access my encrypted partitions...
anaconda does not currently support every single keyboard layout, and we don't have it on our schedule to work on this any time too soon. Sorry.