I don't see why you couldn't. If you were making this from brisket you'd first have to get it to the corned beef stage anyway. Check out the other pastrami post started by dacdots in this forum for more helpful hints.
cm, I've never smoked corned beef myself, but i have a couple of friends that do it alot. They strongly recommend that you soak and rinse the commercial corned beef with a couple of water changes over 24 hours before smoking. If you don't the salt in the cure concentrates to the point of an extremely salty finished product.