It is in DrawingViewStyles collection:
It must be set in each template. It is not a general option.
This would be an example (oDFT is the active Draft Docuemnt object):
If you want to set up them separately then you have to look at the object "DraftFilePreferences" in DraftDocument and the property "DVSTyleNameFromTable".
I didn't test this.
Dim oDFT as SolidEdgeDraft.DraftDocument = oSE.ActiveDocument
Dim dftPrefs as SolidEdgeDraft.DraftFilePreferences = oDFT.FilePreferences
dftPrefs.DVStyleNameFromTable(seDVStyleMapping_PrincipalAndPictorialViews)="Your Style name 1"
dftPrefs.DVStyleNameFromTable(seDVStyleMapping_2DmodelViews)="Your Style name 2"
Hope this helps,