change keyboard layout with X

The most important directory is:
/usr/share/X11/xkb/symbols/

Here you find all existing keyboard layouts.
I would suggest to copy the one which is
very similar to your needs to one of the
keyboards you certainly do not need, e.g:

 sudo cp de af

Then change af:

 sudoedit af

(optional, is done by next step anyway?

now you need to compile it:

 sudo xkbcomp af
)

Now you use it by:

 setxkbmap -model pc102 -layout af

(or by selection of keyboard layout in e.g. kde)