Shoutbox

Well... there is one way you could do what you describe.
You can use the oMessenger object to create a new IM window (just to make sure there's somewhere to send it), then use SendKeys or the equivalent message in C++s SendMessage with the WM_KeyPress (I think).
You can use those to type out a /away message to a window.  Those are the only workarounds that i've seen or heard about though.

Hope that helps