Adding more keyboard layouts to KDE3 (SLD5)
First, launch the command
You will get a window like
Click on "Enable keyboard layouts" checkmark, then from the list on the left choose the language you need and press the "Add>>" button
Some languages may have different layouts available - select on from the list below
and press "Apply"!
(KDE3 has a bug which doesn't let changing the keyboard shortcut for switching layouts, you will need to click on the layouts indicator in the taskbar for that)