[JDEV] Jabber clients that don't take messages, possible?

[Steven Brown]

I'd like to make a custom Jabber 'client' that is designed to run in
addition to normal Jabber clients, but won't take messages away from
those clients.  It should never retrieve offline messages, either (as
this particular client can't display them and would just destroy them).
Is there a way to do this already in the Jabber server (1.4.2) or will I
need to make a custom hack to it?