Custom 404 Error Page

Has anyone found a way to display a custom error page for a 404 error when the requested URL is NOT an nsf?

I have searched this forum, and although several people have asked the same question, the responses given do not work for this purpose. I already have a custom error form for general errors in domcfg.nsf, and custom response headers only effect the headers, not the content.

Surely, someone has found a way to do this in ND6?!