Karabiner code keyboard media keys with native fn on application key

private.xml

<?xml version="1.1"?>
<root>
  <item>
    <name>Code Keyboard media keys</name>
    <appendix>This will bind CODE/WASD the printed values on the media keys to their actual software function.
        * FN+Insert    : Pause / Play
        * FN+Delete    : Previous Song
        * FN+End       : Next Song
        * FN+Pause     : Mute Volume
        * FN+Page Up   : Volume Up
        * FN+Page Down : Volume Down
    </appendix>
    <identifier>private.code_keyboard_media_keys</identifier>
    <autogen>__KeyToKey__ KeyCode::PAGEUP, ModifierFlag::FN, ConsumerKeyCode::VOLUME_UP</autogen>
    <autogen>__KeyToKey__ KeyCode::PAGEDOWN, ModifierFlag::FN, ConsumerKeyCode::VOLUME_DOWN</autogen>
    <autogen>__KeyToKey__ KeyCode::PC_PAUSE, ModifierFlag::FN, ConsumerKeyCode::VOLUME_MUTE</autogen>
    <autogen>__KeyToKey__ KeyCode::END, ModifierFlag::FN, ConsumerKeyCode::MUSIC_NEXT</autogen>
    <autogen>__KeyToKey__ KeyCode::PC_INSERT, ModifierFlag::FN, ConsumerKeyCode::MUSIC_PLAY</autogen>
    <autogen>__KeyToKey__ KeyCode::FORWARD_DELETE, ModifierFlag::FN, ConsumerKeyCode::MUSIC_PREV</autogen>
  </item>
</root>

You must leave jumper 6 off and set some key to fn in the existing key settings