Well mIRC is developed in Britain so the FBI have no authority over it whatsoever. Even if any kind of 'chat tracking' was put into a client as high profile as mIRC without being explicitly stated that it contained such 'features' I'm almost certain beyond any doubt that it would breach some form of law and would leave mIRC Co. Ltd. wide open for lawsuits. Fortunately in Britain the government isn't quite so far ahead in it's ability to circumvent all basic privacy rights in the War Against Terror™.
In short: I'd bet £10,000 that there's nothing remotely like that in mIRC (if I had £10,000 that is), and even if it ever were it would no doubt be discovered within hours of being released, you simply can't hide that kind of tracking.
'IRC developers and administrators' is far more likely to mean the developers and administrators of the IRC daemons and IRC networks themselves. From the server side you could monitor all IRC traffic over that server without any indication whatsoever to the users so it's from there that any government agency would do it's tracking.
