you can download from the public library a module to manage texts from external files, display them and trigger sentences from a list and update text file "live".
this module is (vs) XT text (layer)
here's a demo (in french) for this module:
http://www.vimeo.com/1411563?pg=transcoded_embed&sec=1411563
for a better video quality check this address:
http://www.visionsonore.net/blog/wp-content/uploads/2008/07/vs_xt_textlayer.mov
hope you'll enjoy it