Using a Sun Type 7 USB keyboard in KDE
If you look around, everyone make it complicated. It isn't.
* Settings > Hardware > Keyboard
Select the correct keyboard modal, then on the Layouts tab add a new one for your language, layout, and select the 'type 7' variant.
Move it to the top of the list so it's default.
Enable nothing in the 3rd Advanced tab
* Reboot - you should find the volume and power keys work