Direct attachment or backing box, your choice.
There are mounting holes on each corner for direct attachment
Perfect! So Cat6 wire(s) through the wall, four small holes, four rawl plugs... Done!

I notice that cable mentioned - http://www.netstoredirect.com/cat6-cable/68-excel-cat6-utp-external-cable-ldpe-outer-sheath.html
...is described as "Solid Cable" and doesn't specifically mention "outdoor"?
How about - http://www.kenable.co.uk/product_info.php?products_id=5790