You can do it yourself! it's very easy!
Create new .txt document, for example converter.txt, open it and
write:
NeoDsConvert.exe -bios2
Now, save that file in folder where you have bios, roms, and
NeoDsConvert.exe files.
Change extention of converter.txt to converter.bat
Now you have -bios2 converter. If you want change bios number just
edit the file in
notepad and change -bios2 function to other (-bios3, -bios4....)