- Press
Win+Rto open the run dialog. - Enter
steam://open/consoleinto the box that appears, this will open Steams console.

- In steams console enter this for the English version of the files, see bottom for instructions for other languages.
download_depot 42690 42682 6067691797475126381
download_depot 42690 42683 6381783964590594065
For languages besides english ONLY DOWNLOAD ONE LANGUAGE PACK
Swap out the line
download_depot 42690 42683 6381783964590594065
For the relevent language below.
Spanish
download_depot 42690 42684 2528087911534752870
German
download_depot 42690 42685 3657601166463056212
French
download_depot 42690 42686 7088412265150636376
Italian
download_depot 42690 42687 8273360275068894160
DOWNLOADING DLCS IF OWNED
You can only download DLCs with this method if you own them.
download_depot 42690 42695 9005316271397236436
download_depot 42690 42696 2478272765185873756
download_depot 42690 42697 5810618727794750362
download_depot 42690 42698 5997898371746217629

- These files will likely download to their respective folders in
C:\Program Files (x86)\Steam\steamapps\content\app_42690\depot_42682
C:\Program Files (x86)\Steam\steamapps\content\app_42690\depot_42683

- Download and run this script by double clicking it, it will move all the files to
C:\Games\MW3, this is configurable by editing the variable in the script if desired.
move.bat
If you ever need to verify the game files, this script is an interactive way to pick what files need to be verified, and it will tell you which depots need reinstalled. Once downloaded it will move them to the C:\Games\MW3 by default, and is configurable the same way as the move script from before. (this only includes base game + all language packs, it will be updated for DLCs soon)
mw3verify.bat
To my knowledge the DLCs were not updated and wont need redownloaded, I may be wrong. Feel free to correct me.
Hadi77KSA informed me that they were, I verified this on SteamDB as well. However, you cannot legally obtain the DLCs with this method without actually owning them.
Some of the information here I found from YourPalTaika, I just wanted to provide a more in depth guide since his was a bit lacking in my opinion.
