First of all you have to ensure you installed the KDE options. At install time select KDE (unless you want both).
Then When booting don't automatically go into graphical mode ( I thinkl you need init 3) so you get console login.
Then start kde with kdeinit or startkde -- can't remember the exact command.
This thread has some more info if you don't want to re-install (assuming you've got KDE installed in ther first place).
http://www.linuxquestions.org/questi...d.php?t=206129
(KDE to knome but it should work the other way around)
or
http://www.linuxquestions.org/questi...d.php?t=306385
probably a better solution.
I installed KDE initially so I get KDE automatically when I type startx from the console after boot up.
Cheers
-K