Go to your dashboard and change your language to the second from the bottom. Start Halo 3, invite 4 other friends around the same rank as you and have them change their language to the same one as you.
Get everyone in the same party before you want to get them in the same party. Everyone has to search at the same time.
Everyone is then to go make a game in Lone Wolves but before you go to start the countdown, press X to change the search options to the bottom one, which is search for the same language.
If done correctly, chances are you will be in the same ranked lone wolves game as your friends. Feel free to get achievements or level someone up.