customizing the keyboard layout

[xpol]

To customize my keyboard layout, i have created a new file "my_kbd" for the
default alphanumeric_keys  in /usr/share/X11/xkb/symbols, then i have added
that new file to /etc/X11/xkb/rules/base.lst list.
Also added my new file to the xorg.conf line     
Option          "XkbLayout"  "my_kbd"

Is that the correct way to get my layout both in the character terminals and
in the kde environment?

It has worked for one  year, yet broke a few weeks ago. 
Anything changed in the base.lst format?

thank you 

--
Pol