Why would you want something like this. It sounds as though you want mIRC to be running on someones computer without their knowledge, so you can screw it.
Even if you are not planning to do something like this, have you thought of the people who like using backdoors to control ones computer. This would open mIRC to the virus world as a trojan, which is not good, let alone it can be illegal.
In other words, bad idea.
