This works only for Neo Geo games because it needs Razoola Universal Bios 2.3
Step by step:
1) Download Razoola UniBios 2.3 (google for it) and place them in FBA320 roms folder
2) Start any Neo Geo game. After the "now loading" screen a "Universe Bios 2.3/ Region: Europe/ Mode: Arcade" screen will appear.
3) At that screen quickly press Y+B+A. This will bring up a men? with various options.
4) Highlight Region Setup (Europe Arcade) and press A.
5) Choose any region you want (Japan-Usa-Euro) but when you must choose the Mode (Arcade or Console AES)
press B (Console-AES)
6) Highlight Play Game and press A
7) The game will start. To add a credit simply press Start (because you are in Console-AES mode).
Now the good news. During gameplay press Start+Select. This will PAUSE the game and a new men? will appear with "The Cheats Database" option so, if you want, you can also use cheats. Press Y to exit men? and resume game.