Sorry, Cous Cous is a pasta and is not allowed. Unless they make a whole wheat version, you wouldn't be able to eat that on the SB diet in phase two or three!
It is listed on page 81 of the Good Fats/Good Carbs Guide. It lists the serving size as 1/2 cup 18 carbs and it is listed as limited. At the top of the page it says "Couscous is another good low glycemic index choice to substitute for white rice or white potatoes".
Other limited choices are basmati and white long grain rice while good choices are Uncle Ben's converted rice, wild rice and brown rice. I would say you could eat it on phase 2 but not too often.