I had this when I was going to college and now I miss it a lot. It is a non alcoholic drink.
In the old days of soda fountains, soda was made with two ingredients: syrup and soda water. Soda water is just carbonated water, and the syrup can now be purchased for flavoring coffee and making sno cones.
You need to experiment with the proportions to get the flavor you want, but the recipe is simple.
there's a great site http://www.homemade-dessert-recipes.com/cream-soda-recipes.html which gives original cream soda recipes from the 19th century onwards, you might find something there that would give you a recipe similar to the one you are looking for.