idonen - 5:13 pm on Nov 19, 2005 (gmt 0)

From google:

"To ensure that no one can take advantage of this configuration to view statistics to sites they don't own, we only verify sites that return a status of 404 in the header of 404 pages."

This has nothing to do with whether you have a generated 404 page or a plain one, it only cares that your 404 page does indeed return a 404 header. There's nothing to stop you returning a 404 header *and* a customized page for the end user.