mouseman,
Normally I don't like coding in PowerPoint. I find it more trouble than it's worth, but 90 slides, 3 slides each, 4 seconds to open, 5 seconds to select, 6 seconds to change, 2 seconds to close, etc... boggles the mind!
This should suffice:
Sub SetEntryEffect()
'
' Set entry effect for all objects on slides.
'
Dim i As Long
Dim j As Long
For j = 1 To ActivePresentation.Slides.Count
ActiveWindow.View.GotoSlide Index:=j
For i = 1 To ActiveWindow.Selection.SlideRange.Shapes.Count
ActiveWindow.Selection.SlideRange.Shapes(i).Select
With ActiveWindow.Selection.ShapeRange.AnimationSettings
.Animate = msoTrue
.EntryEffect = ppEffectFlyFromLeft
.TextLevelEffect = ppAnimateByAllLevels
.AnimateBackground = msoTrue
End With
Next i
Next j
ActiveWindow.Selection.Unselect
ActiveWindow.View.GotoSlide Index:=1
End Sub
The key line is:
.EntryEffect = ppEffectFlyFromLeft
this is where you set the effect, mine is flying from left.
I suggest you record the macro doing the effect and see what the official name is for the effect you want to apply.
Hope this helps.