At this time there's no easy way to do such a thing. When CB Activity 4.0.0 releases you'll be able to just use an Activity or Comment field (both fieldtypes are available, but they're currently profile specific) or use global activity messages which will display on every activity stream output by CB Activity. For now I suppose the easiest way is to use a Custom HTML field and simply put your messages as HTML directly in the fields description, which will display on every profile.
Sorry. Any news for me?
Please don't bump posts. See my signature for support business hours.