Easy with custom input mapping...
http://fs-uae.net/input-mapping
For example:
Code:
keyboard_key_rctrl = action_joy_1_fire_button
keyboard_key_kp4 = action_joy_1_left
keyboard_key_kp6 = action_joy_1_right
keyboard_key_kp8 = action_joy_1_up
keyboard_key_kp5 = action_joy_1_down