Instructions
Navigate to a website offering livery downloads (see "Resources"). Download the livery you want to install, and make sure it is designed for the aircraft you wish to use it on.
Open the Windows "Start" menu and select "Recent Downloads." Unpack the downloaded file by double-clicking on it. Double-click on the "simobjects" folder followed by "airplanes." Click on the folder containing the aircraft type that you wish to change the livery on. Locate the "Texture.Q." file.
Navigate to \Program Files\Microsoft Games\Microsoft Flight Simulator X\SimObjects\Airplanes\. Double click on the folder containing the type of aircraft you wish to change the livery on. Drag the "Texture.Q." file from the other window into this window.
Right-click on the "aircraft.cfg" file. Click on "Open with." Select "Notepad."
Locate the matching text below in the "aircraft.cfg" file. Copy and paste the text below over it. Change the aircraft name and number to the one with the livery you are installing.
[fltsim.6]
title=Boeing 737-800 Qantas
sim=Boeing737-800
model=
panel=
sound=
texture=Q
kb_checklists=Boeing737-800_check
kb_reference=Boeing737-800_ref
atc_id=
atc_airline=Qantas
atc_flight_number=VHVXH
ui_manufacturer="Boeing"
ui_type="737-800"
ui_variation="Qantas"
ui_typerole="Commercial Airliner"
ui_createdby="Microsoft Corporation"
Save the file. Close Notepad. Open FSX. You can now use the selected aircraft with the new paint job.