No, you can’t add such a docking socket on bottom side. Therefore you would need a new mainboard and notebook case and I believe such parts are not available for Satellite Pro A120 because it’s not a business notebook.
Anyway, you can use Dynadock as Keany wrote. That’s a docking station that you connect via USB.
Just have a look on official Toshiba website for more details. In my opinion it’s interesting product.