I haven't downloaded it, but it looks like it's for ULUS10566 if that's the name of your version. It'll tell you in PPSSPP what version it is.
Boot up Duodecim in PPSSPP
Press Esc
Game settings
Tools
Developer Tools
Tick replace textures
Then go to Memstick/PSP/TEXTURES/ and extract it all in there. Should be in a folder with the same name as your game version. I don't know if it'll work for any other version than that one.
EDIT: it does, you just need to rename the folder. It looks really good, actually. It's not fully done, but what has been is really good.
Also, unrealated there's a Crisis Core one going on too. Someone asked me about it here a few years ago but I can't remember who or what thread it was in.
http://forums.qhimm.com/index.php?topic=20208.0 @Shademp