It seemed to be rather easy, unfortunately it's not as there isn't any object which can change it's status, there's only a @mq object and the library use @mq.send which basically calls EventMachine#send_data http://eventmachine.rubyforge.org/EventMachine/Connection.html#M000287 which doesn't take a callback. So, if I understand all the included EventMachine magic, we need an object which can change its @deferred_status.

I'd be glad if someone can take a look and confirm (if) I'm right, I never really used EventMachine so I might be wrong.

Thereby I'm postponing this functionality to the 0.8 release.