Something like this will put a combobox over E1 (adjacent to D1):
Option Explicit
Sub testme()
Dim wks As Worksheet
Dim myCell As Range
Dim myCombo As OLEObject
Set wks = Worksheets("sheet1")
Set myCell = wks.Range("e1")
With myCell
Set myCombo = wks.OLEObjects.Add(ClassType:="Forms.ComboBox.1", _
Link:=False, _
DisplayAsIcon:=False, _
Left:=.Left, _
Top:=.Top, _
Width:=.Width, _
Height:=.Height)
End With
End Sub
