Unless you have a subscriber button on twitch chances are this isn't possible. The only reason Sevadus can do it is because he's able to message all his subs anyway. You can't mass message followers/random people.
Re: [twitch-idea] A command to send a msg via twitch?
if you're wondering about that domain, you would need to buy it from a web host like http://godaddy.com then set it up to your liking. you couldn't really do this in mIRC unless you wanted to have it show up in the chat, which would just be a simple msg command.