This page intends to allow remote sessions using "X Display Manager Control Protocol" (XDMCP).
One way to start the X server is trough kdm, and if u want to be able to login remotely to your kde session from a remote machine, you need to allow xdmcp. To do this edit you kdmrc ( /opt/kde/share/config/kdm/kdmrc ) and at the end there should be something like this:
Then you need to restart your X server so the change you just made takes effect:
Now you should be able to login remotely using your prefered session/WM. Enjoy!