1) Start IGPix (the camera icon in the Insors window)
2) Start PowerPoint locally, and load and start the presentation.
3) In IGPix use the "hand" icon and select the window containing the presentation.
4) You are all set. IGPix will report the URL for remote viewing of the presentation - at this point I am not sure if this URL is automatically shared with the other sites or not. (If not just drop the URL in the chat window.)