A while ago I actually tried doing something like that (in C#) and so far I got it to authenticate and send private messages (none are relayed though). It actually took me two server processes running on different ports (directory and chat) to get my PoC working with the chat control.
I’m all in for an MSN Chat revival, as even though I never used it during its run, it still looks a bit interesting to me (protocol-wise and its interface). Also the whole “chat control being ActiveX” thing does really get in the way of properly introducing MSN Chat to a modern audience. Maybe it could just stay in the realm of that old MSN 4.x add-on, but I feel MSN Chat has more potential outside of an extension for an outdated version of MSN Messenger.