http://www.iospirit.com/blog/article/131/Remote-Buddy-and-Boxee-Plex-and-XBMC/

I strongly discourage to use the Plex Harmony profile with any other apps, though, since the Plex Harmony profile contains many errors. F.ex. some IR codes weren't properly recognized by the Harmony when it was programmed. So the raw IR code sequence will just be replayed by the Harmony and what you'll see is that you press a button once, but the Harmony sends the Apple IR codes for multiple button presses in quick succession. Or, alternatively, the Harmony plays it back only once, making short and long presses indistinguishable.

Best regards, 
Felix Schwarz