Welcome to to the forums!
Someone would have to create a custom ROM that was based off of Gingerbread. You might be able to find a launcher that has a Gingerbread theme to it though.
If you flash a cyanogenmod based rom on your s3, then that could work. It won't be gingerbread, but there is a WORKING gingerbread theme you can apply that makes your phone feel like gingerbread.
I don't care about the appearance. In order to read my e-textbook from my phone, I need Gingerbread. It looks like I will have to wait until I upgrade. Thanks.