[Sony Xperia T, TL, TX, V] LastQuark:
Because of my poor memory, I record what I do to root and install roms along the way. If you want to install the latest unbranded and rooted rom, here's the instruction:

Try beginning step 6 first. If there is problem rooting, then start with step 1.

1. Install flashtool (Thanks to Androxyde)

Download here:

http://androxyde.github.com/index.html?1355071460000

- The latest file as of this writing is: flashtool-0.9.9.0-windows.exe

2. Install drivers located in /drivers directory where you installed flashtool

- Click Flashtool-drivers.exe

- I checked Xperia TX driver, Flashmode Drivers, and Fastboot Drivers

3. Download stock AT&T rootable here (Thanks to Spectre51):

- https://docs.google.com/open?id=0ByrrmqPijqISREZpSE16bWdKV1E

- It's good to always have a copy of the stock AT&T firmware in case something happens

4. Plug in your TL to USB. Make sure other drivers are installed in PC. It will ask to install Sony PC Companion. Install it.

5. Run Flashtool. I used Flashtool instead of Flashtool64. (This is all from Spectre51. Thanks!)

- It will ask to connect yout TL. Power off the TL. While pressing low volume button, plug in the USB.

- Drag the "LT30at_7.0.B.1.152_ATT.ftf" file to the window in flashtool.

- Make sure to check "Exclude baseband" to exempt it from being installed. It is ok to leave it unchecked on a stock AT&T rom but just to make sure.

- Once done, disconnect USB and power-on the TL.

- Make sure to enable USB debugging from settings -> developer options. It is not enabled by default.

6. Download ICS Backup and Restore apk. You'll need this. Otherwise, there will be rooting error:

http://xdaforums.com/attachment.php?attachmentid=1343299&d=1348239155

- Save it in your SD card (internal or external)

- Install the apk

7. Rooting the phone (Thanks to Bin4ry):

- Download Root_with_Restore_by_Bin4ry_v17. You can find the file here: http://ul.to/xdevcthz

- Extract the zip file and run "RunMe.bat".

- At this moment, if there are flags in the phone or the PC Companion to update the phone to the latest version. Don't do it. Skip it.

- Click to restore the contents of "RootMe" in the phone. This is in the RunMe.bat instruction also. Phone will reboot and you are done. Your phone is already rooted.

- If you need more info, go here: http://xdaforums.com/showthread.php?t=1886460

8. Download CWM for locked bootloaders (Thanks to Davidmarco, Sharaz22, and Cray_Doze). Make sure to do this first before installing other firmwares.

- Direct download here: https://www.dropbox.com/s/aghj2kmjrvuyyiq/CWM4XperiaT.zip

- More info here: http://xdaforums.com/showthread.php?t=2012738

- Unzip and run install.bat

- Disconnect usb cable and power off the phone

- Power on the phone

- When SONY logo appears, press repeatedly (not holding) volume-down until the phone vibrates. Wait a few seconds and you will be on CWM

- Choose "reboot system". CWM was installed successfully.

9. Download the latest stock and rooted version "195" (Stock-7-0-A-3-195-rooted.zip). Thanks to GregBradley.

- Download the file directly from here: http://d-h.st/wvy

- Transfer the file to you SD card (internal or external is ok)

- Use CWM to install

- More info here: http://xdaforums.com/showthread.php?p=34810891

10. Install SuperSU from Play Store.

That's it!