The OP found the solution (and originally posted it as an edit):
WARNING: By following these steps you will activate your trackpoint and the corresponding keys but disable the touchpad
Step 1:
echo "options psmouse proto=bare" | sudo tee /etc/modprobe.d/trackpoint-elantech.conf
Step 2: Open the following file with a texteditor as root
/usr/share/X11/xorg.conf.d/11-trackpoint-elantech.conf
then, copy the following text into the file and save it
Section "InputClass"
Identifier "Elantech Trackpoint"
MatchProduct "PS/2 Generic Mouse"
MatchDevicePath "/dev/input/event*"
Option "EmulateWheel" "true"
Option "EmulateWheelButton" "2"
Option "EmulateWheelTimeout" "200"
Option "YAxisMapping" "4 5" # vertikales Scrollen
Option "XAxisMapping" "6 7" # horizontales Scrollen EndSection
Step 3:
sudo modprobe -rv psmouse && sudo modprobe -v psmouseenter code here
Finished, trackpoint and the related keys should work now. If not,
reboot/log out and try if it works then.