How to use it

One rom only:
Unix: cat gbongba-xx.gba rom.gb >> rom.gba
Dos: copy /b gbongba-xx.gba+rom.gb rom.gba
Multi roms:
Unix: cat gbongba-xx.gba *.gb >> roms.gba
Dos: copy /b gbongba-xx.gba+rom1.gb+rom2.gb+...+romN.gb roms.gba

Then, load it onto your FA Card or with your fav emulator.