You'd need to start kde from a running X session to enable shutdown, so you'd need to edit: /etc/inittab and change id:3:initdefault to 4
Code:
# Default runlevel. (Do not set to 0 or 6)
id:4:initdefault:
Next time you reboot you should be greeted by kdm or xdm (read /etc/rc.d/rc.4 for a better idea)
gl