I don't have mala on this computer to try, but this might work. If you have mame, point your Mala mame rom dir to your NeoGeo dir. Use the game list editor to make a Mame game list (this should automatically add the rom names for the files.) Then save that and rename the file extension from .mlg to .ml#, # being the number that is associated with Nebula. You can then tell Mala to use that game list for Nebula. Like I said, not sure if this will work, but it's worth a try.