Comment 14 for bug 253785

To change the location of the Playlists folder on your rockbox device you need to create a text file with the extention ".cfg" and then add this line inside that file:

playlist catalog directory: /Music/Playlists

Then load the .cfg file on your device via Settings--> Manage Settings --> Browse .cfg Files

See link below for more useful options
http://download.rockbox.org/daily/manual/rockbox-sansaclipplus/rockbox-buildap4.html#x20-382000D