I was able to just install KDE i think it was in 4.1 rc2 but I wiped my machine and installed rc3 (its my tinkering box) and tried to install KDE the same way, in dom0 running:
sudo qubes-dom0-update @kde-desktop-qubes
but this time it seems to download everything and then the window closes, when i reboot and try to select KDE at the login screen I still only have xfce as an option and when i try to reinstall kde i get output that downloads are skipped because they are already installed and will be saved in cache? not sure where to go next with that?
For what its worth, after the download term window goes away, I am left with the error:
Module or Group “kde-desktop-qubes” is not available
As i mentioned before, I was able to install it in rc2 i think, any reason it shouldnt be working in RC3?