I found this Buttons Mapping 2.txt in the GTA 3 Folder, does this look correct?
#
# Classic Configuration (PS2-like)
#
# --------------------------------
# Syntax: ACTION CONTROL
# --------------------------------
# On Foot
WEAPON BUTTON_B
CYCLE_WEAPON_RIGHT DPAD_DOWN
CYCLE_WEAPON_LEFT DPAD_UP
PED_WALK_LEFT_RIGHT LEFT_STICK_X
PED_WALK_UP_DOWN LEFT_STICK_Y
JUMP BUTTON_X
SPRINT BUTTON_A
EXIT_VEHICLE BUTTON_Y
CYCLE_CAMERA_MODE BUTTON_WHITE
FORCE_CAMERA_BEHIND_PLAYER LEFT_TRIGGER
TARGET RIGHT_TRIGGER
LOOK_BEHIND_FOR_PED BUTTON_RIGHT_THUMBSTICK
LOOK_AROUND_LEFT_RIGHT RIGHT_STICK_X
LOOK_AROUND_UP_DOWN RIGHT_STICK_Y
SHIFT_TARGET_RIGHT LEFT_TRIGGER
SHIFT_TARGET_LEFT UNKNOWN_CONTROL
SNIPER_ZOOM_IN BUTTON_X
SNIPER_ZOOM_OUT BUTTON_A
SNIPER_MODE_LOOK_LEFT_RIGHT LEFT_STICK_X
SNIPER_MODE_LOOK_UP_DOWN LEFT_STICK_Y
# In Car
CAR_GUN BUTTON_B
ACCELERATE BUTTON_A
BRAKE BUTTON_X
HAND_BRAKE RIGHT_TRIGGER
STEERING_LEFT_RIGHT LEFT_STICK_X
STEERING_UP_DOWN LEFT_STICK_Y
CHANGE_STATION LEFT_TRIGGER
HORN BUTTON_LEFT_THUMBSTICK
SUB_MISSION BUTTON_RIGHT_THUMBSTICK
CAR_GUN_LEFT_RIGHT RIGHT_STICK_X
CAR_GUN_UP_DOWN RIGHT_STICK_Y
CAR_LOOK_LEFT_RIGHT DPAD_X
CAR_LOOK_UP_DOWN DPAD_Y
# [CHRISTIANB] the following button's no longer used in the game
# CAR_LOOK_BUTTON BUTTON_RIGHT_THUMBSTICK