You can get pretty close by means of KDE settings only:
Go to KDE's system configuration, then go to "input devices" in the "hardware" section. In this window, make sure you have selected "keyboard" on the left, then open the "advanced" tab. There we are, keeping in mind that you can select and combine the options, this allows for a very flexible setup.
- Placing Ctrl on the Windows key and keeping the alt keys as they are:
- Behavior of the Alt and Windows keys:
- Enable: Ctrl is placed on the Alt keys, Alt on the Windows key.
- Swapping Ctrl and Alt keys, although you lose the AltGr key:
- Behavior of the Alt and Windows keys:
- Enable: Ctrl is placed on the Alt keys, Alt on the Windows key.
- Position of the Ctrl key:
- Enable: Right Ctrl as Alt key.
PS: I'm answering in this old question because it showed up first when I googled it.
I'd switch CAPS LOCK with ctrl. – artifex – 2010-03-05T08:53:58.200