Im pretty sure you would have to do this manually, because i think the only way you would be able to do this 100% accurately. Some people customizes error pages so it would be hard to scan for key words and such.
there will be a querystring on the 404 page of 404;url_of_original_request
__________________
Chris. ->> Links are advertising NOT optimising!! <<-
Indifference will be the downfall of mankind, but who cares? Code Samples | People Counting System