I have gotten a working set of configuration files for using the Tankstick or Duo joysticks from XArcade for those that are interested. These work with the default configuration (PC/Mac Mode 1) of the Tankstick/Duo without having to program another mode. In order to do this, I had to patch the mame4all-pi application (I submitted my patch back so hopefully it will become part of the base code) to allow [ and ] to be mapped to buttons. Make sure you've downloaded mame4all-pi before starting any of the steps below.

First thing you need to do is ensure numlock is turned on by adding the following line before "exit 0" in /etc/rc.local

for tty in /dev/tty?; do /usr/bin/setleds -D +num < "$tty"; done

Next you need to replace the mame executable in /home/pi/pimame/emulators/mame4all-pi/ with the one from the link below (until the patch becomes part of the base code):

https://dl.dropboxusercontent.com/u/7985304/mame

And replace the default.cfg file in /home/pi/pimame/emulators/mame4all-pi/cfg with the one from the link below:

https://dl.dropboxusercontent.com/u/7985304/default.cfg

Optionally, if you'd like to be able to control the PiPlay menu and games list menu with the Tankstick you can replace the file controller.yaml in /home/pi/pimame/pimame-menu with the one from the link below:

https://dl.dropboxusercontent.com/u/7985304/controller.yaml

The key mappings are as follows:

PiPlay Menu
Select game: 1
Back: 2 & 4
Menu: Space
Quit: Left Control & Q

Game/Roms Menu
Start game: 1
Open up jump to letter menu: Space
Move up/down one at a time: Up/Down
Move up/down one page at a time: Right/Left
Quit: 2 & 4

In Game
Quit back to Roms menu: 2 & 4
Menu: 1 & 3
Player one coin: 3
Player one start: 1
Player two coin: 4
Player two start: 2

I made the following changes to /boot/config.txt, but these are optional and could damage your Pi (I overclocked) so use at your own risk:

To get audio working through the HDMI cable I added the following:

hdmi_drive=2
hdmi_force_edid_audio=1

And the following speed and GPU memory settings as recommended by the mame4all-pi developer:

arm_freq=900
core_freq=300
sdram_freq=500
gpu_mem=64

That's it. Lots of games I like play fine and I can just barely stand playing NBA Jam. I'm a little surprised Arch Rivals and Pigskin don't work, but I'm going to see if there's anything I can do to fix that as I love those games. One of my other favorites, Cyberball, works just fine. All the Pacmans are good and even Smash TV works using both joysticks for player one.