I cant seem to find anyway to play CEA on splitscreen 
When on the Campaign menu, press Y and choose My Xbox 360 Console.
You will be able to sign in a guest and play co-op split screen.
I had the same problem. It took me a few minutes to figure this out when I first got the game. While in the campaign menu, press Y and choose My Xbox 360 Console. From there yo’ll be able to sign in another profile or a guest profile. Hope this helps.
> When on the Campaign menu, press Y and choose My Xbox 360 Console.
>
> You will be able to sign in a guest and play co-op split screen.
Also here’s a video that shows you.
Mimi: “Vodka means “Water” in Russian, you know.”
"My name is Recoome, it rhymes with doom, and you’ll be hurting all too soon.”