I'm not aware of any way to control an external player like that unless you break your content into chapters and have the player set to pause at the end of each chapter.
You can lengthen the desired slide on the timeline to keep it visible for longer, but you'd have to use the FF/Skip button on the player if you wanted to move on before the duration was over.
It certainly seems simpler to just pause the slideshow using the player controls and resume when you're ready, but if you need that to happen by itself and only resume manually, you may need to use one of the earlier two suggestions.