I say wire it
x x x
x x x
were x is any number you want.

Then for 6 button games, map:
1 2 3
4 5 6
But for 1 to 3 button games (nplayer.ini), remap them
1 2 3
1 2 3
Then either the top or bottom set will work, and each player can pick which ever set they like. OTOH...
IMO, hotrod/xarcade align the buttons too low compaired to the joystick. I would like to use the bottom set for three button games, but use the top instead because the bottom set is so low. My other CPs have the buttons in the right place, but they are more for specific games. At some point I'll re-do my 6 button panel, but it's not that much of an issue to rush it. Anyway, I guess my point here is if you don't do the remapping as above, were you put the joystick relative to the buttons should effect which numbering you use IMO.