This add-on is not affiliated with XenForo Ltd.
It comes with two themes, dark and light, fully configurable from the Admin CP. As well as the look of the add-on and its position, you can also fully modify the text that appears.
Here's the default text when read more is clicked:
This version uses "implied consent" which is acceptable and the method that most websites are employing.
You can find a more detailed discussion about the Cookie Law here: http://xenforo.com/community/threads/eu-pecr-rules-on-getting-permission-to-use-cookies-how-can-xf-help-make-me-compliant.29690/
You can see a demo of this in action (if you're in the UK) by going to http://www.valvetime.net.