I havnt tried this but in point 3 in this thread you might find what you search for.

3) Howto GUI Login Menu:


sudo apt-get install kdm-kde3

Ignore any errors. there should only be two lines of it fyi. Reboot and you will get a plain GUI login menu for kde that has welcome message for Kubuntu but these are customisable under:
KMenu > System > Settings > System Administration > Login Manager