Asking permission or otherwise trying to get Wal-Mart to go on record allowing concealed weapons is sure to be an exercise in frustration in these litigous times. I'm about as pro-gun as they get but if some customer called me out of the blue and asked me my company's policy on carrying handguns into my place of business, I'd be leery and very careful about how I handled it. Who knows, some nutcase will come in to shoot up the place and then claim that I gave him permission to take a gun into the store.
Just carry the damned gun into the store. Chances are, it will never be an issue because nobody will ever take notice. If, in the very rare and unlikely event you ever have to take the gun out to defend yourself, Wal-Mart will have little to do with it. Law enforcement will take over and judge your actions accordingly. So long as your permits are in order and you have a legitimate case for self-defense, you have nothing to worry about.
Before TN changed it's CCW law last year to allow us to carry in places which sell booze for off premise consumption, it was illegal to carry in TN Super Wal-Marts as they sell beer. Now I carry when I go to Wal-Mart..I try to never let it show. But don't worry over much about it. All they can do is ask me to leave. I haven't seen ONE sign that says no guns permitted.