Bespoke 404 Error Page

[eluser]JamesTaylor[/eluser]
I'm wanting to implement a bespoke 404 page to a website i'm building - I can see that its possible to edit the error_404.php file in application/errors folders but i'm wondering if or how its possible to control it via a controller, in much the same way as each page is handled?

My aim to utilize my template file which has the main site components included such as the header, main navaigation and footer etc. - i then just want to load in in a simple 404 error message which will take on the styling of the rest of the site etc.

Is my aim easily achievable or do i have to dupilcate all the code from my template into the error_404.php file?

Thanks

James