Hello, I also have a R4,U have to download the Cheat.dat file and then put it in your system folder. If u did right it asks you if you want to replace the file (there is already one) and click yes. And whoops your all done. It's possible that the cheats doesn't work, if so chanche the system folders name in _system_ If the do work ignore the thing above.
You will need to use usrcheat.dat. Issues on cheats not appearing, read the Common Issues https://www.romulation.org/forum/index.php?topic=1462.0