I personally have a 2p cp with 4 sticks....the sticks on the right side of the buttons is wired to buttons 3, 4, 5, and 6.
I wrote a controler.ini file for 2 8 way which I use for all the 2 stick games......Robotron, Smash TV, Crazy Climber, Total Carnage, Cloak and Dagger, Black Widow, ect, ect, ect.
That seems to have worked the best for me.