'open embedded workbook for editing
pptShape.OLEFormat.DoVerb Index:=1
'assign workbook to an object variable
Dim xlWB As Workbook
Set xlWB = pptShape.OLEFormat.Object
'enter text in a cell
xlWB.Worksheets("Sheet1").Range("A1").Value = "This is some sample text . . ."
'close workbook
xlWB.Close SaveChanges:=True