[eluser]danmontgomery[/eluser]
Whether you use absolute or relative paths have nothing to do with whether or not you use the url helper or the CI super object...
I'm saying if the controller doesn't exist execution is halted before you have access to these things. If you need to use CI functionality in the 404 page, I'd suggest you use _remap or a catch-all route at the bottom of routes.php to redirect any 404s to your own 404 controller.
