Charise -
I would tackle this by making the awning out of gumpaste and let it dry for a few days. After it is dried I would use royal icing to glue it to the side of the cake. Also depending on how thick you make the awning you could use skewers or toothpicks to help you with some support along with gluing it to the cake.
Not sure this is the best way but the way I would think to do it :) Good Luck!
