You don't need to use Automation to do what you want.
To specify a specific worksheet in an Excel file, use the name of the sheet
in the Range argument of the TransferSpreadsheet.
If you want to do it programmatically, you can use VBA or a Macro.
Open the VBA editor, click on help, type in TransferSpreadsheet. For a
maco, choose the Action. For VBA choose the Method.