It is funny how you say that the mIRC scripting language should just be stripped from the client and created into its own language, but yet, why do this? This scripting engine itself is engineered towards pure IRC use. This would kinda be like taking the apache scripting engine and making it compatible with all programs, do you catch my drift?
This might not be what you guys are talking about, but just reading the replies its the first thing that came to my miind.
I don't think that mIRC will ever be open-source, there would be too much controversy from people that have already bought licenses and so forth...
But anyways, signing off...