did you see this?
DO NOT QUOTE INSTALL INSTRUCTIONS BELOW THIS LINE IF YOU REPLY TO THIS THREAD!
THEY ARE OUTDATED, AND KEPT ONLY FOR HISTORICAL REFERENCE!
Most of the information after this line is outdated.
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Also read this:
http://www.internettablettalk.com/fo...&postcount=202


in short: install the package, click Sliderotatesettings in Extras, select (re)install xrandr kernel and wait ~ 1 minute. Voila. rotation in Diablo.

It could be easier I guess, but I think it is as easy as it needs to be already.