When it comes to scent, fish will generally feed on something that emits Amino Acids, Proteins, Oils, and Minerals, because these things will benefit the fishes health, all fish have virtually the same Amino Acid and Protein requirements. I don't really believe in scent unless I am catching fish few and far between, if I were fishing for Kokanee and got into a school of them, the last thing I would worry about is scent unless I were fishing my offering motionless. A school of fish is going to create some competition for each fish, so if you jigged a spoon or something in front of a school, about 30-60% of the school is going to race towards the thing because each fish wants it first.
You could probably go to a health food store and get a quality Amino Acid Complex along with fish oil (Cod liver oil is a KILLLLER, did I really just say that out loud), this would be the best start at making a great scent for a variety of species.