I don't know how to make a game list that I can edit outside of Mame for FBA.
Don't have mala handy, but IIRC, the other gamelists are allgames.mlg1 or allgames.1mlg or something like that, with each number being a different emulator. You could convert one of those with mlgconverter.exe
There's also the option of using the multiple emulators in one list workaround stickied at the top of this forum.
If done that way, it would show up in your MAME list and pull the info from mame.xml, but would launch in FBA.
You'll need to have a good understanding of batch files and how to launch the game via command line though.