What software do I need to configure the SMI2? Do I need a specialized cable?

To program this RS485 Display you have to use SMI2 Configurator.

You can find it either on the product page or on the CD that is delivered together with the device.

To connect the SMI2 to the PC you need a USB cable and a USB-RS485 interface converter, for example, the IC4 from akYtec.