1. Make c:\gamegear. You have to use this path to avoid editing a bunch of files.
2. Extract or copy BSMGGFIN.ARJ and BSMGGFIN.001 to c:\gamegear
3. Extract to the same dir (BSMGGFIN.ZIP)
4. Extract to the same dir (loads of dirs and files)
5. Make sure you have HEX2BIN.EXE, padbin.exe, make_rom.bat in c:\gamegear
5. Run make_rom.bat (you can double-click it)
6. Done!

I tried to make it not necessary to use c:\gamegear but the path is hard-coded in the linker scripts in the original code. It might work on other dirve letters, I didn't test it.

Maxim, 30/11/2007