I don't speak Czech, but I experimented on my keyboard. Mine is set to pc105,
us intl (acentos) layout, both in xorg.conf and KDE Control Centre Keyboard
Layout. You really only need the latter, but defining it in xorg.conf means
all X programs know about the keyboard.
Type AltGr-Shift->, which produces a dead hachek, then type either lower or
upper case 'c'. Voilà! AltGr is the right Alt key. Typing AltGr-Shift-> twice
types the hachek without a letter underneath. All the dead keys work like
this.
If you want to configure xorg.conf, this is what I have (adjust for your
keyboard, but this is pretty generic):
Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
Option "Xleds" "1 2 3"
Option "XkbModel" "pc105"
Option "XkbLayout" "us"
Option "XkbVariant" "us-acentos"
EndSection
us-acentos is fantastic! It should be the default, as accents are required in
many English words or words commonly written in English, like voilà, naïve,
pie à la mode, please apply with a résumé, etc.
