Orbited is not allowed to Spoof the IP, however the IRC server is.
Make sure your IRC server has support for CGI:IRC (Unreal does this,
Inspircd IRCd can do it, more with modules). That allows for a certain
IP (orbiteds) to supply the clients IP via different techniques (such
as sending it as a password) and the IRC then sets it as the real
one.
The easy and ugly solution is to hack the Orbited core, but as you
probably figures, that's not really a good idea (however I must admit,
that's the way I'm doing it right now).
More information on
http://groups.google.com/group/orbited-users/browse_thread/thread/69e07f17058aa591/97a217c170ab6169?lnk=gst&q=orbited+internals#97a217c170ab6169
As Joboc is so rightly pointing out, a better solution would be to
create a simple proxy server as a stand in between. When I have the
time I guess I'll do it.
Regards,
Niklas