What's wrong with changing the Mame settings? You usually have to remap some button or change spinner sensitivity etc anyway. That's pretty dang lazy... 
Sounds like you need to map a button for each coin slot.
I'm guessing you have no idea what we are talking about 1up..... You see on the old tmnt and similar 4-player cabinets, each character had a dedicated joystick, button set, and coin slot. To play leonardo you had to use the player 1 position, raphael 2 player ect....
Well this is fine if you have a 4 player panel, but if you don't then mikey and donnie are always unselectable.
Remapping the keys in this case you be time-consuming and retarded as every time you decided you wanted to use a different character you would have to remap the joystick inputs, coin input and two button inputs. Not to use your method, would not be considered lazy, but smart. Our solution is the only one worth doing, but as pj would say "Thanks for Playing!

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