Warmtoe has released a Neo Geo only version of MAME for the DC, you can download the unscrambled bin file from here. Only the smaller sized NG ROM’s (around 4MB or less) will work due to the amount of RAM the DC has, so don’t bother trying to get the 100+MB ones to run, because they won’t.

If you’d like more info or to discuss this release you can in this forum topic Thanks to Hollywood Hasney for the news!