We don't know of a software-only solution for teleprompting. However, Listec
makes the A-5000, a complete hardware system available from Listec. The A-5000
is a black box that connects to the printer port of a Macintosh. Any
application that prints via a Chooser device can be used to supply the words
for prompting. A print driver that outputs ASCII is needed--most daisy-wheel
printer drivers provide ASCII output from the Macintosh. The A-5000 requires
its input to be in ASCII text form.
The output of A-5000 needs to go to a teleprompting display device. Listec
makes a variety of display devices, including the transparent glass prompters
used by podium speakers and the video screens mounted on studio video cameras.
For more details, search the Tech Info library under "Listec."