See the Skin Thread:
http://www.mede8erforum.com/index.php/topic,7539.0.htmlHowto change a skin:
To load a skin -- just download it and unzip /unrar it to a folder. In X2 navigate to this folder and press the ‘Menu’ button and select ‘Set to Skin Option’ The new Skin will be loaded into flash memory and used as the new default. You can revert back to the original default skin at any time by selecting the option ‘Restore Default Skin’