First: This method works for all European, Latin, Korean, etc servers ...
Well, what we will do is convert our songs to .ogg and then pass them to the S4 League Jukebox.
Collect all the songs you want and put them in a folder (to make it more orderly)
Steps to follow:
First we need a program to convert the songs, I recommend Free Mp3 Wma Converter V2.2 to download
Note: You can use any converter that is easier for you to use.
Once installed it will be configured as shown in the image above.
Now we go to the top and click on Add Files and choose the songs to convert.
Once converted we go to the destination folder, in this case I leave them on the desktop:
Let's go to the folder where they have S4 League and inside there will be a folder called BGM (if they do not have it create it)
Your songs should already appear on the Jukebox, let's check.
Then they just choose them for the map they want and that's it.