I have a feeling that this functionality is possible but it will probably need to be added to mod_fifo.c as a feature request. Announcing the caller's position in queue is really a function of the queue system itself and not some third-party script. That being said, a question for the devs is this: if I know the uuid of a call that's in a fifo queue can I displace the audio (be it MOH, fifo_chime, etc.) and playback the caller's position (or any other audio for that matter) without disrupting the queue system? Just curious.
-MC