Download the greasemonkey addon here https://addons.mozilla.org/en-US/fir.../greasemonkey/
When that has finished installing click on this link userscripts.org/scripts/source/117314.user.js and the script should install
Click on the edit emblem option in your platoon and you should see a big yellow button that says "Use custom image" click on this
You should see this come up
Click on the big box then it should bring up a small menu
Click select image then once you have selected which picture you would like click "Save emblem".
Your done! You can also use .gifs if you wish.
Credit goes to Twoogle