Well... I have never configured joystick movements to key presses. Usually games just work without a need to touch Poseidon configuration. Just assign controllers in the game or e-uae etc itself. Only thing to check in Poseidon is that how Lowlevel library emulation is set. USB joystick has to be mapped to one emulated port to be working on amiga games etc.
With analogue controllers (like racing wheel), you may have to configure correct ranges etc in the action tab on the Poseidon settings...
