Another good article on Pemmican.
How to make it, how to eat it and why it is good for your prepping food stores (it is a very long term storage food, if made correctly).
http://www.offthegridnews.com/extreme-survival/explorers-ate-it-it-stored-for-50-years-heres-their-recipe/Yes, you can add other things to it, but these tend to reduce the storage life. It is better to add these other ingredients at the time you cook with it.
Items such as dried berries, salt and sugar might be added, but do note the caution on effecting the storage life of the pemmican itself.