Our setup needs to specify under which ip the bot runs, in order to show the right ip to the irc server (we don't want to disclose internal ip's to irc users). This ip would be taken from the bot configuration file (like bindto : aaa.xxx.yyy.zzz
The php method used doesn't allow to set a bind address, but it can be done, cfr. http://stackoverflow.com/questions/4765269/specify-source-ip-using-fsockopen

Is it something you'd consider? If not and if I work on it, would you accept a patch?