The game runs in DOSBox, so you can use DOSBox's keyboard mapping feature to map any key to your joystick directions/buttons.
Once the game is started up, hit CTRL+F1 to bring up the virtual keyboard. Click on the key you want to map, then near the bottom, click the "Add" button, then press the corresponding joystick direction or button you want to map it to. Once you've done that for all the keys you want to map, click the Save button, then Exit.
This should work for any game that runs in DOSBox.