Enki wrote in a former post:
\"The key to rotation in x is the /usr/X11R6/bin/xrandr command ...
$ xrandr -o left
the above command will rotate the screen into \"portrait\" mode, ie default for 5500 serioes
$ xrandr -o normal
this one will put it back in \"landscape\" mode, ie default for 7x0 series\"
Good luck!
Peter