To make your own black cat bone you don't just boil a black cat alive, you have to do it at midnight on the night of a full moon. (duh!)

Boiled the cat until the skin and meat falls off and then take the bones to a river that runs north. Throw the bones in the river, the bone that will make you invisible will float south. Now fish that bone out and start having fun with your new powers. (But watch out for those pesky animal rights activists and christians!)

source: gramps