Method 2: (For all firmwares with an unlocked bootloader)
1. Make sure that your bootloader is unlocked using the Asus Unlock tool. 2. Unzip the ZIP file below (it says Padfone 2, but this method is successfully tested on multiple first generation Padfones). 3. Connect your Padfone via USB, run padfone2_root_tools_en-US.bat.
Make sure to follow the instructions on screen properly!