You should be able to use the <cferror> tag in
application.cfm or use method "onError" within application.cfc to
direct the template not found error or any other CF error to
specific pages. eg.
<cferror type="request" template="error.htm">
BTW with regard to giving away the type of app you're running
accessing a ".cfm" page is pretty much a give away on the
technology.
-Tim