So you realise remoting is never going to get through a firewall? Well, it can, but any sysadmin that would open those ports needs a big slap.
COM/Remoting is pretty much dead. I'd strongly suggest thinking in terms of passing messages rather than objects, and look at hosting WCF within your application. You can do triggering of events via WCF callbacks - but you need to examine the scalability of it carefully.