Bear with me, Steve...YOU know what you are doing...I have no clue. Please describe to me how you are currently running your presentation, what you currently use to advance your slides, and what it is you think you want to sync to your manual show.
Let me tell you this...no matter how you're doing it, without some sort of timeline that corresponds to a "hit" or "event" or whatever you want to call it.... If your show is totally random...hire a lighting director. Anything I know of has to start and end at a fixed point in time. You can, indeed, PAUSE an audio track midstream. But, I know of nothing that is going to be a one-click solution to what I now envision you are doing.
Please elaborate, or I'm helpless to provide you any guidance. Thanks.