I know it can be done. I'm just debating doing it myself or paying $10 for a flashing service. I've heard both good and bad about one called cyberflashing and I don't know anything about any of the other services.
There are many different flashing services that have windows apps you run on a regular computer. You connect the phone to the computer running the app and they go in through the Internet and do everything. I haven't found cheaper than $10 and some are over $50.