Okay, -thinking back alittle- smell is a sense just like vision and hearing. I remember from class, Native Americans had several methods for experiencing lucid dreams and OBE's, one of those methods involved inscense. They made them from plant matter and medicines. Look up spiritual inscense or something relavent.
Also, I've heard of people that remember certain smells from dreams that contained some significance to them. A young lad whom I'm friends with told me about her dreaming about her grandmother who died when she was very young. But she remembered that her grandmother carried a certain scent to her. She smelled the same scent every time she experienced this recurring dream where her grandmother would sing to her. She learned the lyrics thru these dreams. One day, she told her mother about the dreams and the song. It turned out that the song was very old and her grandmother sang it to her when she nursed her as a baby. So when ever she sings the song, she remembers the smell.

Anyways, I got a little off sorry, lol. But I hoped that helped.