XinMo Manual Key Mapping?

[dragonninja]

Hello all, Just started using RecalBox and extremely impressed with the ease of setup and configuration compared to Retropie - great job. I'm using v4.0.0-beta2 on my Pi3 with a Xin Mo USB adapter, running just MAME (for n0w). I don't want to use GPIO since I need the Pi to be quickly disconnected. It's installed in my Bartop arcade. Now, since it's a custom bartop I have non-standard buttons (js1 is P1 and js0 is P2 - plus I have other external buttons) and I'd like to manually map my joysticks. I'd assumed I'd be able to easily do this through Retroarch, but I can't seem to find the place to do this. Any ideas please?

[dragonninja]

OK, so it looks like I can use a custom config file? eg.  snes.configfile=/path/to/my/configfile.cfg What's the syntax for MAME?   mame.configfile=/path/to/my/configfile.cfg  ?

[acris]

for mame2003 mame2003.configfile=/path/to/my/configfile.cfg