You will need to edit /etc/pluto.conf as root.
you can go to KDE Desktop, open a Konsole:
sudo kate /etc/pluto.conf
Password: <whatever root password you entered>
this will open the pluto.conf file to edit, you can then look for the line that starts with
LogLevels=....
Add a ,36 to the end. This will turn on ZWave logging.. (This is defined in src/DCE/Logger.h if you're curious.)
Then reload the router. You will then see Z-Wave logging information in your DCERouter.log.
-Thom