New Post: Logging failed URLs from custom 404 page using hostnames

I've set up a multi language webapplication using Composite hostnames found here: http://docs.composite.net/Configuration/UrlConfiguration/Hostnames.

Now I would like to log which URL the user could not find. I am struggling to figure out how to do this. I've tried custom razor functions, but Request.UrlReferer is always null. The FileNotFoundHandler.ashx handler inside Renderers, never seems to be hit.

Any idéas?

Cheers
Jens