SEE VIDEO SUMMARY TO DOWNLOAD THESE MODS
Sora, Roxas, and the stage mod are all in one pack for convenience. Credit to ultima espio for Sora, umjammerlammy2 for Roxas, and Kousen for Dive to the Heart.
umjammerlammy2 DA original download link - http://2playerwins.deviantart.com/art/Roxas-The-key-of-destiny-367362763
Link for Sora, Roxas, Dive to the Heart - http://www.mediafire.com/?7r09zdw2qq21t03
Roxas is easy to use, simply copy the five .edat files into the folder on your PSP with other D012 DLC and he'll be usable as Zidane DLC2 in-game. That's it.
Using Sora and the stage mod are more complex, instructions can be found in this thread and on the relevant links on the first post.
http://dissidiaforums.com/showthread.php?12240-General-Dissidia-research
Please do not ask me how to use them, the reason being I'm not that proficient myself and needed help getting my Sora and Aqua to work, and once accidentally corrupted my ISO and had to copy the entire thing onto my PSP fresh. I don't want to cause problems or confuse people by, as they say, the blind leading the blind. If you can't figure it out from that link, post in the thread and ask, the people are friendly, they helped me and they've helped others, they'll help you if you ask.
