import win32com.client
from win32com.client import constants as C
propName = "TheProperty"
gridDataName = "TheGrid"
siProperty = Application.ActiveSceneRoot.AddProperty( "CustomProperty", False, propName ) 
gridData = siProperty.AddGridParameter(gridDataName).Value 
gridData.ColumnCount = 3
gridData.RowCount = 3
for row in range( 3 ):
        gridData.SetRowLabel( row, "Row %d"%row )
        for col in range ( 3 ):
                if row == 1:
                        gridData.SetColumnLabel( col, "Col %d"%col )
                gridData.SetCell( col, row, "%d,%d"%( col, row ) )
# Set the diagonal as read-only
ROcells = [ 0,0, 1,1, 2,2 ]
gridData.SetCellReadOnlyFlags( ROcells, True ) 
Application.InspectObj( siProperty )