I actually found the way by using scripts on layout enter. Sorry!
If you want to save yourself some time, I have a method for handling this.
Put a text box on the layout with the appropriate orientation as the text ( Landscape/ Portrait ). Set the conditional formatting so that Get ( WindowMode ) < 4 the text size is 500. Name it "page.orientation".
Now you have a developer-only visible box that you can use in a generic script.
The psuedo code script would be
Set Variable [ $orientation ; GetLayoutObjectAttribute ( "page.orientation" ; "content" ) ]
If [ $orientation = "Portrait" ]
Print Setup [ Portrait ]
Else If [ $orientation = "Landscape"
Print Setup [ Landscape ]