Whilst we await the official Android Jelly Bean update for Sony Xperia handsets, there is a way that you can get a close to stock Android 4.1 experience on your phone right now. If you don’t mind tinkering with your phone and unlocking the bootloader then you can download a custom ROM such as CyanogenMod 10.
We get many requests asking us to post a tutorial on how to get CM onto their phones, so we thought we’d post a quick guide going through the steps to get CM10 on the Sony Xperia T. The basic premise is similar to other Xperia phones too, so you can broadly follow this guide even if you don’t have the Xperia T.
Tutorial to install CyanogenMod 10 on the Xperia T
[Xperia Blog absolves itself from any responsibility should something go wrong. Please proceed with caution and at your own risk.]
Unlock the bootloader
The very first step before you can install any custom ROM is to find out whether you can unlock your Sony Xperia bootloader. Do this by opening the dialler and enter *#*#7378423#*#* to access the service menu.
Tap Service info > Configuration > Rooting Status. If “Bootloader unlock allowed” says Yes then you’re good to go. Unfortunately if it says No, then you cannot unlock the bootloader.

To unlock your bootloader, follow the instructions from Sony Mobile here. However, you may want to read a few tips below that supplement the instructions that Sony provides.
YOUR WARRANTY WILL BE VOID IF YOU UNLOCK YOUR BOOTLOADER
Notes:
– You will need to request an unlock bootloader key from Sony Mobile, so be prepared with your name, email address and the first 14 characters from your IMEI number (hit *#06# to find your IMEI).
– Make sure you have Java SE installed on your computer.
You will also need to install the Android SDK. Once installed, when running the programme make sure you run it as the administrator (right click the icon to run as administrator).
– To connect your phone in fastboot, hold the power button and volume UP on your Xperia T at the same time whilst connecting the USB. The notification LED should turn blue.
– The Fastboot file should be found in the following folder: C:\Program Files\Android\android-sdk\platform-tools
Use cmd.exe to fastboot into your phone using the following path [cd C:\Program Files\Android\android-sdk\platform-tools].
– To know if you are connected properly, enter the following: fastboot.exe -i 0x0fce getvar version
If you get a response back such as what is seen below then you are connected properly.

– To unlock the bootloader enter the following: fastboot.exe -i 0x0fce oem unlock 0xKEY
[KEY is your unique unlock code]

Install CyanogenMod 10
1) Download the following files:
– CM10 zip file from here. Look for the ‘mint’ code to find the right download code for the Sony Xperia T.
– GAPPs zip from here. Make sure you choose correct device and ROM. We downloaded the version for the Xperia T (LT30p Mint) with filename ‘gapps-jb-20121011-signed’.
2) Place the zip files in the root of your phone’s internal storage or SD card folder. Turn the phone off.
3) On your computer, unzip the CM10 zip file from step 1. Place the ‘boot’ image file in “C:\Program Files\Android\android-sdk\platform-tools”.
4) Fastboot into your phone by opening the command prompt (cmd.exe).
Type the following: cd C:\Program Files\Android\android-sdk\platform-tools
Once you are in the right Fastboot folder, type: fastboot flash boot boot.img
Then type: fastboot reboot
5) Now you need to enter into the Xperia T’s recovery.
Disconnect phone and switch on. When you see the purple LED light indicator, press volume UP repeatedly.
6) You should now be in recovery mode. To navigate use the volume up/down buttons to move up and down. Use the power button to select the option.

7) Navigate to ‘Wipe data/factory reset’ and run. Then navigate to ‘Wipe cache partition’ and run.
8) Now select ‘Install zip from sdcard’ and browse to where your zip file is located and then run the CM10 program.
9) Do the same above for the GAPPS zip file downloaded in step 1.
10) Now run ‘Wipe cache partition’ then select ‘Reboot system now’.
11) Congratulations, you should have CyanogenMod 10 successfully installed.


Trouble shooting
If you have any problems you can reset the Sony Xperia T as follows:
Volume Up + POWER (for 10 seconds) -> Battery reset [Device will vibrate once]
Volume Up + POWER (for 15 seconds) -> Hard reset [Device will vibrate three times]
Via xda-developers.