Bury it in a pile of damp leaves for a few days. That's what I do with any new item I use for hunting (camo, climber, etc). That seems to remove artificial smells faster than just airing it out. The other thing you can do is set it up down wind of a camp fire (or just burn some brush). Cloth and plastic seem to absorb smoke like a sponge for some reason. Deer don't seem to be alarmed by the smell of wood smoke.