MacOS – How to map function key (F1-F12) to perform like they do with builtin keyboard on Macbook

Try the free KeyRemap4MacBook from the site below

http://pqrs.org/macosx/keyremap4macbook

You could try using a private.xml like this with KeyRemap4MacBook:

<?xml version="1.0"?>
<root>
  <item>
    <name>test</name>
    <identifier>test</identifier>
    <autogen>__KeyToKey__ KeyCode::F1, VK_CONTROL, KeyCode::BRIGHTNESS_DOWN</autogen>
    <autogen>__KeyToKey__ KeyCode::F2, VK_CONTROL, KeyCode::BRIGHTNESS_UP</autogen>
    <autogen>__KeyToKey__ KeyCode::F3, VK_CONTROL, KeyCode::EXPOSE_ALL</autogen>
    <autogen>__KeyToKey__ KeyCode::F4, VK_CONTROL, KeyCode::LAUNCHPAD</autogen>
    <autogen>__ConsumerToKey__ KeyCode::F5, VK_CONTROL, ConsumerKeyCode::KEYBOARDLIGHT_LOW</autogen>
    <autogen>__ConsumerToKey__ KeyCode::F6, VK_CONTROL, ConsumerKeyCode::KEYBOARDLIGHT_HIGH</autogen>
    <autogen>__ConsumerToKey__ KeyCode::F7, VK_CONTROL, ConsumerKeyCode::MUSIC_PREV</autogen>
    <autogen>__ConsumerToKey__ KeyCode::F8, VK_CONTROL, ConsumerKeyCode::MUSIC_PLAY</autogen>
    <autogen>__ConsumerToKey__ KeyCode::F9, VK_CONTROL, ConsumerKeyCode::MUSIC_NEXT</autogen>
    <autogen>__ConsumerToKey__ KeyCode::F10, VK_CONTROL, ConsumerKeyCode::VOLUME_MUTE</autogen>
    <autogen>__ConsumerToKey__ KeyCode::F11, VK_CONTROL, ConsumerKeyCode::VOLUME_DOWN, ModifierFlag::OPTION_L | ModifierFlag::SHIFT_L</autogen>
    <autogen>__ConsumerToKey__ KeyCode::F12, VK_CONTROL, ConsumerKeyCode::VOLUME_UP, ModifierFlag::OPTION_L | ModifierFlag::SHIFT_L</autogen>
  </item>
</root>

I don't know if it works with all keyboards, but it does work with my Kinesis Advantage.

See http://lri.me/keyremap4macbook.html for more information about using KeyRemap4MacBook.