Macbook Pro Key mapping for Lubuntu is quite irritating. If you are using virtualbox and need to map the keys correctly, just click on the GB or US icon in the bottom panel. Choose the top option and unlock the panel by clicking on set default. Then look for your keyboard. Mines a macbook pro and works nicely (mac78 is the option). Hope this helps.
Terminal command version can be found here: https://help.ubuntu.com/community/Lubuntu/Keyboard