404 page - more info, please

[eluser]victorche[/eluser]
[quote author="Twisted1919" date="1296410771"]Create a controller, make it load an error view, then give the controller name to the "404" route.[/quote]
Thanks, but can you be a little bit more specific?

I want to be able to redirect to it, when ... for example I need a way to redirect to this 404 page, when there is no id in the database, for a news controller for example...
I mean, if I have /news/12 (existing news) - it will be displayed
But if I have /news/13f45qa (non existing id in the db) - then redirect to 404

I am making the check for a valid id in the controller and according to this - sending the user to 404