1. Create a playlist. This is quite simple to do, go into the music section of your PS3 menu, select playlists, press triangle to create a new one. Call is KONAMI_PES
A space will be added after the last letter of PES, delete this. Not sure why, but you need to for it to work.
2. Now, unzip the chants and put them onto your USB device. It helps to create a folder called MP3. Insert the device into your PS3, go to the music folder, open your saved data utility, where you should find your USB device. It may say that nothing could be found, if this is the case, press triangle and select "display all". Copy the chants to your playlist KONAMI_PES
3. Enter the game, and go into the teams section of the editing. Let's say for example you want to add the Arsenal chant. Select "cheering stance" and you should have a choice between "Default" "Pattern" and "MP3 library" Select from MP3 library, and the file "Arsenal.mp3" or something along those lines should be there.