[eluser]Dam1an[/eluser]
Hmmm... Ok, you can use get_instance as it's not available at that point

You could always use $_SERVER['REQUEST_URI'] but that gives the URI from the web root and starts with a forward slash, so you might get a bit more data then you need, but you should be able to work something out from there
But there must be a more elaborate method... maybe a hook?