If you'd modify mibbit to send the hostname using the USER token then you could also add irc.scarynet.org, send me a message if you've done that and give me a list of ip's you use for the outgoing connection. Below is the way I implemented cgiirc support, and this can also be used by mibbit. (Sending the USER token the below way is doing it the right way anyways). most ircd's ignore the hostname parameter since they perform there own resolving. So I reused this to transfer the host of the connecting client between a webchat and the ircd in combination with a so-called W:Line (webchat).
* m_user * * parv = sender prefix * parv = username (login name, account) * parv = host name (hostname if webchat) * parv = server name (ignored) * parv = users real name info */