Rotating my screen output

or: Who ate my xorg.conf?
Oh. SuSE did, as the xorg.conf file is deprecated for newer versions of Xorg. Right.
Which posed a bit of a problem, as I needed the file to make xrandr work. Xrandr is a console app able to flip your screen by multiples of 90° (actually, it can do a lot more) via
xrandr -o left #right, inverted, normal
To enable xrandr, xorg.conf needs the following option enabled:

Section "Device"
     Identifier "Card0"
     Driver "nvidia"
     VendorName "Unknown Vendor"
     BoardName "Unknown Board"
     BusID "PCI:1:0:0"
     Option "RandRRotation" "true"
EndSection

If (and only if) xorg.conf is empty, log in on a text screen as root:

rcxdm stop #stop the X server

Xorg -configure #write new xorg.conf

cp /root/xorg.conf.new /etc/X11/xorg.conf #copy over old one

rcxdm restart #restart X

The autogenerated xorg.conf is pretty generic (see it in the quoted section), so don't do this if you have a more specific one written by e.g. your graphics driver setup. Testing the new file from the root console as Xorg proposed (X -conf xorg.conf.new) only gave me a black screen, but it worked fine after restarting X.
There is a pretty krandr plasma widget, but even after all of the above it only managed to turn the screen upside down, so I'd recommend just setting general keyboard shortcuts (with khotkeys) for the xrandr commands.
BTW: Mouse output is not rotated!