Perhaps
this addon has what you're looking for?
Similar affects can be gained with the /who command. Not all networks have the same /who flags, however, you might try:
/who +Mh *hostname/IP*+M searches all channels you're in.
+h searches for a hostname or IP.
Also ask in the #Help or #mIRC channels of the network you're on, they should have some information.
Have fun!
Regards,
