I havnt seen any sticks made from cow horn ,Wtaer buffalo is the best to use the horn is solid.But you can make inlaye with it .I have carved my wifes intial on a piece of flattened horn its simple to use.
just cut it in slices then cut it in the middle boil it and press it flat in the vice it only takes a few mins,Draw a image on it and carve it its only like finger nails. pretty soft