I got some Kola Nut from a spice store. It's is pretty earthy and not that much like the Coca-cola it helped make famous.
I'm planning a Kola Lychee Saison. I only have 2 oz of Kola so I'm not sure if it will be that noticeable in a 5 gallon batch.
I was going to make a cold brew tincture, filter out the components, add the water part of the tincture at 5 mins and the remaining nut material at 10 min.