This version of the VNC server allows to remote control the real display, e.g. display :0
apt-get install x11vnc
Create the file /home/username/.x11vncrc with the following content:
#x11vnc command line options # display :0 rfbport 20000 usepw forever loop bg
Create /home/username/.kde/Autostart/startX11vnc:
#!/bin/sh killall x11vnc &>/dev/null sleep 10 x11vnc
Make sure it has the correct ownership and permissions:
chown username:username startX11vnc chmod 750 startX11vnc
Start x11vnc manually the first time to allow for setting up the vnc server password. Afterwards, x11vnc will start on default when kde is starting up.
cd /home/username/.kde/Autostart/startX11vnc ./startX11vnc