Using a PC/Mac and a pen/external HD

    * Download the .p3t file for the theme you
      want to install.
    * Get an USB pen (or external HD) and create the directory
      PS3.
    * Inside the PS3 directory create another one
      called THEME.
    * Copy the .p3t file into PS3/THEME on the
      pen.
    * Insert the pen on the PlayStation 3 and turn
      it on.
    * Go to Settings - Theme settings - Theme
      and click Install.
    * Look for the theme inside the pen and
      install it.
    * Go to Settings - Theme Settings - Theme,
      pick the theme and click apply.


Some great places for great help and resources.

http://forums.maxconsole.net/forumdisplay.php?f=78
http://www.psp-hacks.com
http://www.psp-hacks.com/forums/