We have a patch to KDE System Settings to support modules which have to be run as root. The highest profile user is system-config-printer-kde, i.e. the printer settings in System Settings, because system-config-printer-kde currently does not support the PolicyKit authentication the GTK+ version uses.
How to test
- Boot to KDE Plasma Desktop
- Start KDE System Settings
- Enter the printer settings
- You should get prompted for the root password.
- Setting up your printer should work.