Part of the beauty and fascination of the Cowichan knitting is the history and the entire process developed by the Coast Salish tribal women. The wool they use is treated to retain the natural lanolin giving the resulting garments natural waterproofness so vitally necessary in our wonderfully dry :rollseyes: climate of the Northwest. In addition it's never dyed, all the colors are natural wool colors from their sheep. I don't remember what breed they have.
Here's a link to a 60's era pattern on sale at etsy. There are some others from that era available there too. You might also try ebay.
IIRC starting in the 70's or 80's the tribes got serious about keeping the patterns to themselves and making sure there was a certification process for all genuine Cowichan knitwear. Growing up, I remember seeing this stuff and it's wonderful to the touch.
The link Susan P. gave has some good representations of the patterns so if you know how to work from a chart you might be able to imitate some of the patterns. I've never worked with wool like that, so can't give ya any advice on a wool that similar.
Let us know what you decide to use and definitely give us pics!