You'll need a USB to RS232 converter for this and also an understanding of the command prompt.
You'll also need to know the multidrop address of the meter you want to switch on.
(It is usually the last 3 digits of the meter serial number, or 001.)
You also need java installed on your system. (java.com/download)
Unzip the file as230.zip to your computer.
When at site, plug the USB to RS232 converter into your laptop.
Go to the modem and plug the RS232 cable out of the modem and into the USB to RS232 modem.
Now run the command prompt and navigate to the folder you unzipped.
Find out what COM port the converter mounted on.
Run the command:
switchon COM1 001

You should hear the breaker when it switches on.
Plug the cable back into the modem.