/* HID Joystick Mouse Example
   by: Jim Lindblom
   date: 1/12/2012
   license: MIT License - Feel free to use this code for any purpose.
   No restrictions. Just keep this license if you go on to use this
   code in your future endeavors! Reuse and share.

   This is very simplistic code that allows you to turn the
   SparkFun Thumb Joystick (http://www.sparkfun.com/products/9032)
   into an HID Mouse. The select button on the joystick is set up
   as the mouse left click.
*/
#include <mouse.h>
int horzPin = A0;  // Analog output of horizontal joystick pin
int vertPin = A1;  // Analog output of vertical joystick pin
int selPin = 3;  // select button pin of joystick
int rclPin = 2;  // select button pin of joystick

int vertZero, horzZero;  // Stores the initial value of each axis, usually around 512
int vertValue, horzValue;  // Stores current analog output of each axis
const int sensitivity = 100;  // Higher sensitivity value = slower mouse, should be <= about 500
int mouseClickFlag = 0;
int rightClickFlag = 0;

//int invertMouse = -1;        //Invert joystick based on orientation
int invertMouse = -1;         //Noninverted joystick based on orientation

void setup()
{
  pinMode(horzPin, INPUT);  // Set both analog pins as inputs
  pinMode(vertPin, INPUT);
  pinMode(selPin, INPUT);  // set button select pin as input
  digitalWrite(selPin, HIGH);  // Pull button select pin high
  pinMode(rclPin, INPUT);  // set button select pin as input
  digitalWrite(rclPin, HIGH);  // Pull button select pin high
  delay(1000);  // short delay to let outputs settle
  vertZero = analogRead(vertPin);  // get the initial values
  horzZero = analogRead(horzPin);  // Joystick should be in neutral position when reading these

  Mouse.begin(); //Init mouse emulation
}

void loop()
{
  vertValue = analogRead(vertPin) - vertZero;  // read vertical offset
  horzValue = analogRead(horzPin) - horzZero;  // read horizontal offset

  if (vertValue != 0)
    Mouse.move(0, (invertMouse * (vertValue / sensitivity)), 0); // move mouse on y axis
  if (horzValue != 0)
    Mouse.move(((horzValue / sensitivity)), 0, 0); // move mouse on x axis

  if ((digitalRead(selPin) == 0) && (!mouseClickFlag))  // if the joystick button is pressed
  {
    mouseClickFlag = 1;
    Mouse.press(MOUSE_LEFT);  // click the left button down
  }
  else if ((digitalRead(selPin)) && (mouseClickFlag)) // if the joystick button is not pressed
  {
    mouseClickFlag = 0;
    Mouse.release(MOUSE_LEFT);  // release the left button
  }

  if ((digitalRead(rclPin) == 0) && (!rightClickFlag))  // if the joystick button is pressed
  {
    rightClickFlag = 1;
    Mouse.press(MOUSE_RIGHT);  // click the left button down
  }
  else if ((digitalRead(rclPin)) && (rightClickFlag)) // if the joystick button is not pressed
  {
    rightClickFlag = 0;
    Mouse.release(MOUSE_RIGHT);  // release the left button
  }
}</mouse.h>

Print enclosure and file down inner tracks so that the joystick PCB slides in easily

De-solder pins from joystick breakout board

Use wires to make the following solder connections:

Solder GND on Joystick to GND on Arduino

Solder 5V on Joystick to VCC on Arduino

Solder VRX on Joystick to A0 on Arduino

Solder VRY on Joystick to A1 on Arduino

Solder SW on Joystick to Pin 9 on Arduino

Solder tac button to Arduino using GND and Pin 2, insulate with heat shrink tubing

Connect Adruino to PC and upload code using Arduino IDE

Disconnect and reconnect Arduino and it should be detected as a mouse input