This isn't entirely to your spec, but Messenger can already do this.
See here on my blog: http://messengergeek.spaces.live.com...DA1!2651.entry
So if you start Messenger with msnmsgr.exe /busy, you'll sign in as busy.
Microsoft MVP - Windows Live Messenger
MSN Messenger/Windows Messenger
MessengerGeek Blog: http://www.messengergeek.com
Messenger Resources: http://messenger.jonathankay.com
(c) 2009 Jonathan Kay - If redistributing, you must include this signature or citation
"D@xxxxxx" <email@example.com> wrote in message news:OEOaUtmKKHA.3424@xxxxxx
> Hi all,
> I suggest this feature for Messenger. I'd like a new command line parameter
> for MSNMSGR.EXE to start Messenger into a specified status.
> Example: msnmsgr.exe /s [status_number]
> Status numbers:
> 0 = Appear Offiline
> 1 = Available
> 2 = Busy
> 3 = Away
> Best regards,