Whatever program is used, I offered the probability that you would more than likely be able to pause the auto slide show, and if so, then manually change the slides as required. - Which is what Nick is looking for.
iMark confirmed that he does the same thing with ULead.
As I stated, - I would think this may be possible with other slide show programs, - but I obviously can't know that for sure.
..... Is that satisfactory?