After releasing my 'Update to .253' thread, I've figured it is something you might want to do your self, maybe because you like to use your own created FTF, or even want to modify your ROM a bit before flashing. This guide will help you through it, as secure and successful as possible!
Anyone can do it!
There is no need to unlock your bootloader to work this guide, however it did help me out of some sticky situations myself, as long as you keep a cool head while working on your ROM, you'll be able to get out of any situation.
The XDA mantra: MAKE BACKUPS!
Before you do anything on your phone, make sure you create a solid backup first. As CWM and TWRP both do not backup your internal storage, create a backup of it's contents too before trying to install your very own ROM.
Flashtool version 0.9.x.x (the latest) - Windows / Linux / Mac
Needed to flash your phone, also needed to create the FTF bundle. The Linux version is already installed in the VM but you can download any other version too, to do the flashing and FTF building before hand in a desktop enviroment you are accustomed to.
[GUIDE] Download ANY firmware customization from Sony & create an FTF with Flashtool
This thread will help you make an FTF file for your DIY project, as we already have this excelent thread I will save myself the trouble of creating a guide for that
VMWare Player (76Mb) (Free for non-commercial use) and [NUT]'s UbuntuHost VM (Bittorrent: 4.84Gb)
The VM you download is OK to use on any 4.1.2 ROM as base.
If you wish to use a 4.2.2 ROM, you will need the DIYGuide UPDATE PACKAGE 1 (Bittorrent: 169Mb).
If you wish to use a 4.3 or 4.4 ROM, you will be needing DIYGuide UPDATE PACKAGE 2 (Bittorrent: 159Mb). Flashtool however needs to be updated to 0.9.15.0 if you are going to build a 4.4 ROM
See the index below for the link to the guide post that explains how to use it.
This you will need for the tricky bits, as modifying a ROM is safer on a Linux host with less chances of breaking file permissions. As most of the world around us uses Windows, I've created a VM to support you in your tasks. I've installed the Linux tools you need, for me this VM works just fine.
The VM needs about 10Gb space on your pc and you need around 1Gb of free RAM when trying to use it smoothly.
This VM also contains a build script, simple but effective, which will create the (unsigned) flashable zip for you, grabbing all the files it needs along the way and giving you time to edit what ever you want during the building process.
I've made sure you have fastboot and adb commands to be found in the PATH variable, and that the connection to most android phones and tablets will most probably work just fine. You can do adb and fastboot commands to your phone without having them in the directory where you keep the files, easy to use!
The VM has one user, which is called XDA Community. To log in on Ubuntu, use the following credentials:
This user has SUDO privileges, so expect to type that password again when prompted to do so while installing packages or even when running the rombuilder script.
Download and install WinRAR or 7Zip to be able to unpack my VM.
Included in the ROM you will build using this DIY Guide
Your DIY ROM will be rooted with SuperUser (or SuperSU when you used an update package), including the reboot fix. It will also include XZDualRecovery 2.3 RELEASE (or newer if you used an update package). So you will end up with a cool ROM!
You will be able to use my AROMA ROM Mutator package to fix your JB 4.1 ROM if anything might fall to pieces in the future regarding root. You'll also be able to use it to make the switch from SuperUser to SuperSU using the mutator, if you might change your mind in the future.
Chapter 1: Introduction and Prerequisites
Chapter 2: Installing VMWare Player and getting 'UbuntuHost' running
Chapter 3: Preparing the FTF for NOOB use
Chapter 4: Preparing and Extracting the ROM
Chapter 5: Building the (unsigned) flashable ZIP
Chapter 6: Installing your DIY ROM
Addendum: How to replace the recoveries to suit your device
Addendum: How to update your VM
Frequently Asked Questions