altering keyboard layouts

[hw]

Hi,

how do I alter a keyboard layout?

I'm not referring to picking another layout via the settings in kde. 
I'm trying to figure out how to create my own keyboard layout which I 
can then pick in the settings.

There doesn't seem to be a program to edit keyboard layouts, and there 
is no indication as to where the existing layouts are stored.  We should 
be able to see that in the settings.

Since there are some layouts, there must be some way to create and to 
alter them ...