Here's a script to xmodmap the dpad and rotate the screen. Also included is the xrandr binary, which is a CLI for the RandR extension, and is used by the script. Install them both to executable places (I put xrandr in /usr/bin, and rotate.sh in /home/user/apps) and invoke as:EDIT: Use the script below, if you want to be able to rotate one notch clockwise or counterclockwise from current position.
EDIT: Script rezipped; now this zip contains the most recent version of the script, able to rotate one notch clockwise or counterclockwise from current position.