For Persona 4:
- Copy 303108.key (I think someone posted the link here) to the game folder
- Run cryptserver.exe and it will automatically recognize the key. Don't close the window!
- With cryptserver.exe opened, run the game with RMIDGod_inject.exe
You also need RFID folder on root c:\ and RFIDGod.dll within that folder (all available at http://8ch.net/1cc/res/622.html)
Also, ucrtbased.dll, vcruntime140d.dll and iDmacDrv32.dll are required to be in the game folder!
I managed to run it, but my PC seems to be slow for this game particularly.