Hi n,
The qCaptionDisplay has no capabilities to change dinamically the CaptionId ((ie using a session, Url parameter, etc). The CaptionId is used to identify the list item and display the corresponding text.
You can try building some custom code (ie js code) that would change that CaptionId dynamically on the page. I've never tried but it may work.
You say "the qListForm in DisplayItem mode doesn't appear to work on an ordinary page that is not a form."
Can you please elaborate? I'm asking this because I have no issues creating a page (web part, wiki, etc) and use qListForm there.
Using a qListForm in DisplayItem mode would do it.