From http://www.stepmania.com/wiki/Configure_Keyboard_and_Dance_Pads#Linux :
For most dance pads, joydev and analog modules are required. Xbox Dance Pads require the xpad module. If they are already compiled with your kernel, try:
modprobe xpad (for xbox pads)
If not, refer to the manual of your distribution how to get it (you can also download the kernel sources from kernel.org and compile your own kernel yourself).
Then look for some test program, like joystick. Install it with your package manager or compile it yourself.
sudo apt-get install joystick
And launch :
You might need to link /dev/input/js0 to /dev/js0 by typing:
ln -s /dev/input/js0 /dev/js0
(I modified it a bit, now it's working on Ubuntu)
I hope this helped you,