For those who are not able to get it to work, don't put the line at the end of the text, i put it between the second and third line( i'm using notepad ++ ) and now it works. Remember to check the box read-only in the properties of the .cfg or it won't work.
PS. I looked on the site you took this guide and in the answers they were suggesting this, so I tried and it works 100%
Well. With the included config_mp everything is fine. You just have to watch that your the host from the BEGINNING not like joining a 1 vs 1 3rd Cage match even if you're the host then, it doesnt work.. well it didnt worked for me