Arduino Leonardo bootloader mode

Hi guys.

So I'm trying to follow this guide to make an old throttle work (Standalone Cougar TQS (Throttle) – Part III - Uri_ba's pit build blog and part I and Part II).

In the guide he's using a Pro-Micro and I'm using a Leonardo. The only difference on the pinout is that I've used A4 on the last analog input which he uses an external ADC.

From the guide it reads:

Installation

Connect the Arduino Pro-micro to the computer, Drivers may be needed.
press the reset button twice in rapid succession to force device into "bootloader" mode.
Your computer will now Identify a new device, please note this device's COM port.
from the AVRdude folder, run the "upload_code.bat" file. In the window opened, type the device's com port number (eg. if device is on COM12, type "12").
double press the reset button of the arduino to force it into bootloaded mode again, and hit Enter. The code will now be uploaded to device. once completed, the device should register as a new joystick.

Problem is that I can't seem to get the Leonardo into the bootloader mode using this methode and uploading the "upload_code.bat". I also guess I need to change the code that's beeing uploaded since I'm using the A4 pin, but I don't know how.

Any help on this or if anybody else has followed this guide before using an Arduino Leonardo?