Messenger Object models...

There is a well define Object Model of MSN Messenger exposed using COM and is easy to use.
Can any one explain/discuss me is Yahoo Messenger is exposed in that way. I found it has object model but everything is so elusive, I cannot understand anything.
I am working in a dot com company which wants to know out how many messengers are running on client's machine and what are their friends list. I cleared out MSN enumeration. Its time to get into YM.

Any expert there...... :confused: