Step 1 : use command "viewport" in AutoCAD to create named viewport (s), such as "view1" to SE Isometric viewport in my case.
Step 2: use the following code:
...
Dim myview As AcadViewport
Set myview = ActiveDocument.Viewports("view1")
ActiveDocument.ActiveViewport = myview
...
@kenneth8848 I think he needs to set the Visual Style to something other than "2D Wireframe"