Shoutbox

You can actually set up a combination of quicktext/custom status to do most of what you want.

Using the settings shown in the attachment you can set it so when you set a custom status (which you can call busy, and be seen as busy) and someone talks, it sends a quicktext which sends the message then blocks them.

It should be a pretty simple script though so I'll have a go at that anyway in a bit.


Edit: You have to use the Custom status rather than the default WLM one