вот сигнатура метода
Sub AddButtonDefinition(DisplayName As String, InternalName As String, Classification As CommandTypesEnum, ByRef ClientId As [optional] VARIANT, ByRef DescriptionText As [defaultvalue("")] BSTR, ByRef TooltipText As [defaultvalue("")] BSTR, ByRef StandardIcon As [optional] VARIANT, ByRef LargeIcon As [optional] VARIANT, ByRef ButtonDisplay As [defaultvalue(kDisplayTextInLearningMode)] ButtonDisplayEnum, Result As [out, retval] ButtonDefinition*)
пример из мануала
Dim oControlDefinitions As ControlDefinitions
Set oControlDefinitions = oApp.CommandManager.ControlDefinitions
Dim oLargeIcon As IPictureDisp
Dim oSmallIcon As IPictureDisp
Set oLargeIcon = LoadPicture(App.Path & "\Large.ico")
Set oSmallIcon = LoadPicture(App.Path & "\Small.ico")
Set oButtonDefinition = oControlDefinitions.AddButtonDefinition( _
"Display Name", "invrSampleCommand", _
kShapeEditCmdType, "CLSID of the AddIn", _
"Description Text", "Tooltip", _
oSmallIcon, oLargeIcon, _
kDisplayTextInLearningMode)[code]