Option Explicit

'Change the five constant values below to suit
'*****************************************************************
Const ppFileName As String = "my documents\your PP folder\your PP.pps"
Const numSlides As Integer = 10 'number of slides in the show
Const exposureTime As Integer = 2000 'exposure time in milliseconds
Const ZStartPoint As Double = 0.0 'where Z starts from
Const ZIncrement As Double = 0.005 'the Z increment
'*****************************************************************

Dim objPPT
Dim objPresentation
Dim s As Integer

Set objPPT = CreateObject("PowerPoint.Application")

objPPT.Visible = True

Set objPresentation = objPPT.Presentations.Open(ppFileName)

Code "G90" 'absolute distance mode
While IsMoving()
  sleep 10
Wend

Code "G0 Z" & ZStartPoint 'start Z at wherever
While IsMoving()
  sleep 10
Wend

Code "G91" 'incremental distance mode
While IsMoving()
  sleep 10
Wend

For s=1 To numSlides
  Code "G1 Z" & ZIncrement + ZIncrement 'lift Z a couple of tads
  While IsMoving()
    sleep 10
  Wend
  Code "G1 Z-" & ZIncrement 'lower Z a tad
  While IsMoving()
    sleep 10
  Wend

  objPresentation.SlideShowWindow.View.GotoSlide (s) 'show the next slide
  sleep exposureTime
Next

Code "G90" 'back to absolute distance mode
objPresentation.Close
objPPT.Quit