I hope this doesn't break etiquette answering my own question, as I know how touchy mods can be about following protocol. But I found this, which can provide a total time for the slide show. It is based on the time set for the automatic transition of the slide (Transitions->Advance Slide->After:). In the Slide Show ribbon, you can disable "Use Timings" so that you'll have control over advancing the slides while presenting.
This won't provide a slide countdown on the presenter's view, but I suppose I can live without that and just enter the expected time I should be at on the top of my notes. The add-in above would seem to provide a countdown on the presenter's view, but I won't be able to use it at my venue, so it's not an options.
I based this macro from here, The PowerPoint FAQ. I have modified it a little bit so to show the times in "00:00" format, and the total time at the bottom instead of separate pop-up. To use it, just create a go to View->Macros, and create a new macro "Total Time". Copy and paste the code below:
Sub TotalTimes() Dim oSld As Slide Dim strMessage As String Dim lngTotalTime As Long Dim strSlideMin As String Dim strSlidesec As String ' Use this to collect times for ALL slides: For Each oSld In ActivePresentation.Slides ' Or comment it out and uncomment this to get just the selected slides: ' For Each oSld in ActiveWindow.Selection.SlideRange strSlideMin = Format(Int(oSld.SlideShowTransition.AdvanceTime / 60), "00") strSlidesec = Format(Int(oSld.SlideShowTransition.AdvanceTime Mod 60), "00") strMessage = strMessage _ & CStr(oSld.SlideNumber) _ & vbTab _ & strSlideMin & ":" & strSlidesec _ & vbCrLf lngTotalTime = lngTotalTime + oSld.SlideShowTransition.AdvanceTime Next oSld ' Comment these out if you don't want to see them strMessage = strMessage & vbCrLf & "Total" & vbTab & Format(Int(lngTotalTime / 60), "00") & ":" & Format(Int(lngTotalTime Mod 60), "00") MsgBox strMessage 'MsgBox ("Total time: " & CStr(lngTotalTime)) End Sub
The original code also includes a section to write to a text file, which I cut out since it didn't meet my needs.
I am so very very surprised MS doesn't have this info available within PowerPoint. It seems like a rather intuitive bit of information that they would include by default.