I realize that mob heads require an orientation, but I still think that it is a bug that when you try to summon a mob head through falling sand, it always is summoned as plain sand.

I am trying to build a dance game where it uses the new player account mob heads (recently added by Marc Watson) with the arrow heads to show people where to move, but no matter what i try, i can't get the mob heads to work, by using the falling sand in command blocks. I always get sand. any help here would be appreciated. Even if I have to orient my machine to accommodate a default head direction.