Hit the 'info' button on your MCE remote & you'll get a menu that includes "rotate"
frodes: sorry, I'm not familiar w/ that remote, but it seems like you have an .ini file where you can define your keypresses so it seems capable of the function. MCS "info" button is equivalent to a "show context menu" (which is keyboard F9 in MP - see the complete list of keyboard mapping here http://wiki.team-mediaportal.com/KeyboardShortcuts).