This chat I had with your tech support guy explains it:
Me: Are there instructions someplace on how to integrate a PowerPoint presentation into XSplit? I can import a PP file into a Scene, and a separate PP Slide Show Viewer window opens. I can scroll through that slide by slide, but I don't see a way to just choose specific slides. What if there are 50 slides in the presentation, and I just want to show numbers 8, 12, 23, 35, and 48? I don't see a way to jump from one to the next. I seem to have to scroll through them all.
Them: Hi there, Rick! Oh okay i see... this is currently a limitation on XSplit's end. We won't be able to jump from slides that are more than one slide apart from each other. Perhaps what you can try is to create 5 scenes, then for each scene import your presentation file, then scroll to your preferred slides so that for each scene the preferred slides would have already been displayed
Me: That doesn't work. If I switch to a particular slide in one of the scenes