Search your computer for plutonium.exe and open file location. Drag the exe into one of your main drive folders like C:\ if you are on windows.

Now that plutonium.exe has the path C:\plutonium.exe we can add it to steam.

Go to manage game on black ops 2 in steam and click on properties
add C:\plutonium.exe %command% to the launch option field like the screenshot below. If your plutonium.exe is on a different drive like D:\plutonium.exe then you have to change the path to D:\plutonium.exe %command%

Now you can click play on black ops 2 on steam and it will lauch the plutonium launcher. Choose the game you want to play and enjoy! Your playtime will be tracked and you will have access to all steam features just like you would playing the game normally.
This method works for all games plutonium supports (and actually any game on steam). If you want to track zombies, multiplayer, or a different cod game it is the same thing. Just add the launch option to those games on steam and you will be able to click play and get all steam features.

Once in-game you should be able to open the steam overlay.

Go to controller settings and enable steam input:
Now you can configure whatever controller you want and it will work with plutonium!

Use a playstation controller or maybe some switch joycons with gyro aiming!

Note: Selecting a server in the server browser menu will still require keyboard and mouse.