This is how I have mine, in the pic below

Notes:
I use Joy2Key to map both my d-pad and left thumbstick to: 7698
This way I can switch between the d-pad and left thumbstick when I want to..
For example: in a shoot-em-up, I'd use the thumbstick mostly, but on a really
intricate scene, I'll switch to d-pad

Though, for Bullet - both thumbsticks are awesome. good luck!
best regards,
- dink