I actually don't know nuts about pad, but this is based on my past experiences.
If it's a Dualshock 2.0, if you don't press the analog button between the two analog sticks, the analog sticks won't be active. So inputting using the left analog stick will be the same inputs as on the D-pad, ie: moving the left analog stick up = pressing up on the D-pad. Conversely, if it matters, moving the right analog stick up will be inputting triangle. So you can just set the directional controls in the game to the D-pad and turn your analog off, and it should work fine.
If you're using anything other than a Dualshock 2.0, I don't know anything else. Sorry.