I've found a work around... (do this while the game is shut down)
Get the blizzard unpacker firstly:
http://www.blizzard.com/support/wow/?id=aww01669p
Next:
Rename your world of warcraft/interface/framexml folder (i used framexml-mod).
Go into your World of Warcraft/Data Folder
Rename interface.mpq to something else (I used interface1.mpq)
Rename patch.mpq to interface.mpq
Then:
Run the blizzard unpacker.
This will unzip all of the patch files to the default Framexml folder since it thinks its unpacking the interface.mpq.
Next:
Move the files you need to modify from the framexml folder to your framexml-mod folder.
Finally:
Delete the new framexml folder.
Rename the framexml-mod folder back to framexml.
Rename your interface.mpq back to patch.mpq.
Rename your interface1.mpq back to interface.mpq