Here is the issue. When using lr-imame4all as the emulator for mame4all you can (Not) get TAB to work. So changing back to mame4all as the emulator you can then enter the TAB screen.
The key here is enter the MAMEUI menu here (TAB) keyboard and be sure to choose Input (General). Now here you want to set your joystick with multiple buttons items listed below, but you still want your keyboard to still work when something goes wrong.
So set what you see below. Once you put a joystick item in it erases what was there for keyboard you then need to his ESC on keyboard and then put back in the key from keyboard that was there originally you can see what they were below. Once you have this all done you no longer will need a keyboard for playing mame4all.
Config Menu - J1 JoyButton 7 = (RTrigger) or Keyboard TAB
Reset Game - J1 JoyButton 5 = (RBumper) or Keyboard F3
UI Cancel - J1 JoyButton 12 = (RStick Press) or Keyboard ESC - this will allow you to exit the menu and even the emulator since Select + Start (Does NOT) work for mame4all
1 Player Start - J1 JoyButton 9 = (Select) or Keyboard 1
2 Player Start - J2 JoyButton 9 = (Select ) or Keyboard 2
Coin 1 - J1 JoyButton 8 = (Start) or Keyboard 5
Coin 2 - J2 JoyButton 8 = (Start) or Keyboard 6
These settings will be saved under under /configs/mame-mame4all/cfg and in default.cfg. Save this file for later use and incase you format and start over. You will also want to save your retroarch-joypads/MicrosoftX-Box360pad.cfg and XboxGamepad(userspacedriver).cfg and last but not least your /configs/all/retroarch.cfg or /configs/mame-mame4all/retroarch.cfg even though these should be the same just depends on which one is actually being used.
Now if you take everything from my 2 other posts and this one then regardless of what you use everything should work properly and normally for these 2 mame emulators and the use of 2 xbox 360 wireless controllers.
mame4all = lr-imame4all and mame4all
lr-fba-next