Add yourself to the mIRC mail list, it will fulfill the same task as an update checker.. Except it is even better, as you don't need mIRC open. If you really want an update checker, it is not hard to script one, and maybe a good project for you to learn some mIRC scripting..
A native mIRC addition would have zero benefits over a scripted one. And a possible negative impact on the webserver. If khaled had very few downloads of mIRC, i think it would be worth it, but I don't think that's the case.