This can be done on Mission 3, "Blood and Rust". This was recorded on Easy difficulty. All you need to do is exit your titan and jump onto an enemy titan for "Cowboy Up". Continue doing this until you kill an enemy titan for "You Can Be My Wingman". You can reload the checkpoint if you are unsuccessful.
Here is a video guide with English commentary for this achievement!
Here is a playlist of guides for this game!
https://www.youtube.com/playlist?list=PL-HeW6XkKdUL1_8Q01lMy...