Well thanks for the quick replies. I will use animations if necessary, but it would be slightly more irritating than having it in the text object as well.
As far as the script is concerned, that's what I tried to use unsuccessfully. I don't want the message window itself to be over the character's head, just an icon or graphic. As far as I'm aware, when you make the message non-floating and non-re-sizable on most speech bubble-type scripts, the graphic disappears, which makes it kind of pointless.