Filemaker 13 error-page/ErrorDocument Edit

Am running a two-machine deployment of Filemaker Custom Web Solution on OS-X using only PHP and would like to edit the error document(s) for the server.  

I've already altered the document on the Apache side (HD/Library/Filemaker Server/HTTPServer/conf/httpd.conf, which I do not think is ever used) but when I attempt to edit the Tomcat error-page, the server is reported as "not responding" and, indeed, does not work.  The file I attempted to add an error-page directive was HD/Library/Filemaker Server/Web Publishing/publishing-engine/jwpc-tomcat/fmi/WEB-INF/web.xml.

The reason I wish to do this is that I used to have an XSLT deployment that I have changed to PHP.  And when users still attempt to access the old login page (something like https://server.com/fmi/xsl/pronounce/index.xsl) they now get an error that reports "Custom Web Publishing Technology disabled; WebDirect is turned OFF" and I would simply like to redirect them to the new PHP login.

This error is reported by a "special" error document that is rendered because the path includes "/fmi".  A default error page is rendered if the path does not include /fmi which says "Object not found!  The requested URL was not found on this server. If you entered the URL manually please check your spelling and try again.  If you think this is a server error, please contact the webmaster…"

Is it possible to edit either of these error documents and if so, how?  Thanks in advance.