How to Change the standard Error Pages in EP 7.0..?

Dear Experts,

We are using NW 2004s EP 7.0 SP 12 Server.

Please give me a solution to show Custom Error Pages(with simple message using HTML or JSP) instead of standard Portal Runtime Error message for Portal Applications or all the java Exceptions in WebDynpro like NullPointerException or JCO Exceptions and file not found exception.

I searched a lot regarding this on SDN and checked SAP Note 795699 and SAP Help link--SAP Library - Using Java

In Help link process only Dispatch error working.404 Error also working that to some times only. Reaming Error Page also i need. 

But couldn't get any good solution for Portal and WebDynpro Applications as the Note and Help Link only talks about web.xml (simple servlet or Jsp web applicaiton).

Please let me know whether it is possible with E.P 7 SP 12.

Thanks a lot.Image may be NSFW.
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Thanks and Regrades,

Durga Rao.