How to Root and Flash ROMs on your Wind Galaxy S3 (SGH-T999V)
You'll need to root your phone. Someone has already confirmed that this works for Wind SGH-T999V.
Here's how to do that:
Then go here for some ROMs. Now some of the ROMs clearly state they are compatible with Wind Mobile. But for the ones that don't state it, I am hearing they still work.
DISCLAIMER: As usual, root and flash ROMs at your own risk. I didn't come up with any of the methods shown in the links above. And I am not a developer. I take no responsibility should you end up with a dead or damaged phone.