property ExPrint.PageOrientation as PageOrientationEnum
Specifies the default page's orientation.

TypeDescription
PageOrientationEnum A PageOrientationEnum expression that indicates the page's orientation.
The PageOrientation property specifies the page orientation. The PageOrientation property must be called before any call of Settings property. Use the Settings property to change settings in the printer dialog. 

The following sample changes specifies an A4 Landscape page, and specifies that margins must be measured in millimeters:

With Print1
    Set .PrintExt = Grid1.Object
    .PageOrientation = exLandscape
    .Settings(exDisplayInch) = 1
    .Settings(exPaperSize) = 9
    .Preview
End With