Using the ED pilot texture template I modified it to look like a WWII pilot in the 8th Air force. Thanks to forum memeber Basco1 for providing the reference image.
your P-51 skins are located here: (DCS Game Root Directory)\Bazar\Liveries\P-51D
1. Pick a skin you would like to add the WWII pilot to. Lets say USAF Big Beautiful Doll, for example.
2. Copy/paste the files from the "WWII US 8th Air Force Pilot Skin" into the USAF Big Beautiful Doll folder.
3. Within the Big Beautiful Doll folder is a file called "description.lua" you can open the file with notepad but it is better if you open it with Notepad++ (You can download Notepad++ here:
http://notepad-plus-plus.org/ )
4. Copy the following text:
{"pilot_P51_patch", 0 ,"P51_8th_patch",false};
{"pilot_P51_body", 0 ,"pilot_8th_WWII",false};
5. The link below is an image of the description.lua file. Replace the highlighted text line shown in the image ( {"pilot_P51_body", 0 ,"empy",false}; ) with the text you copied in step 4.
http://i865.photobucket.com/albums/ab215/Kane822/Temp2_zps2e23628e.jpg
6. If it's not there already, copy/past this text:
id = 4 -- US
into the very bottom of the description.lua file.
When you are all done it should look like the image in the like below:
http://i865.photobucket.com/albums/ab215/Kane822/DCS/Temp2_zps5662f253.jpg
If you are still having trouble check out this thread in the form:
http://forums.eagle.ru/showthread.php?t=92303&page=3 -- My install instructions are in post #29
