This is the code you are looking for:
sheet = app.SchematicSheetDocuments.Open(design_name, sht_num)
view = app.ActiveView
For n = 1 To zoom_level
I have made some assumptions that you know how to properly set app and design_name, and declare the rest of the relevant variables here. If any of that is not clear, post up further questions and we can cover them too.
This works very well...