Csound1,
>There is no audio over VGA, so how would that work?
The VGA-to-HDMI converter (link above) has a separate audio input. There are similar devices with audio capabilities from other sources (for example, http://www.aten.com/doc_data/pdf_dm/vc180_converter_ss_en.pdf). These converters may or may not work together with the DVI-to-VGA adapter mentioned in the PowerBook manual, and they may or may not work with the HDMI input of this very TV.
>As I said before it depends on whether the TV has an audio input that can be active at the same time as a separate video input (that the Mac can use).
That should not be too difficult to determine (a good start could be to read the technical specifications and the user manual for the TV in question).
>Don't simplify this too much, you're leaving bits out.
It is not that complicated. We do not even know whether sound through the TV is needed in this case. My intention has been to provide ideas/options, not necessarily a ready-to-use pre-packaged solution. As I said, a few experiments may have to be carried out.