First, the infamous black cat bone.
I have to admit something here. My uses of the cat bone are not entirely traditional hoodoo. Let me give you a snapshot.
If you ever read “The Once and Future King,” you might recall that Morgause, the Queen of Air and Darkness, was introduced to the reader via a vividly grotesque episode in which she is in the process of boiling a cat alive. She does this to find the bone that will render her invisible. Being Morgause, she loses interest way before anything exciting happens. T. H. White calls this spell a “piseog”  and says that while the “little magics” run in her family, she’s not a great witch like her sister. Well, that would be the attention span problem, I guess. Anyway, this is a traditional use of the black cat bone. For more information on this incredibly well-known spell, see the medieval grimoire attributed to San Cipriano .
Another one, not mentioned in the San Cipriano material, is the use of the bone to return a lost love. Unfortunately, in much of the available recorded material, tradition has it that you have to go through the same de-catting process in order to get the magic bone that will do the trick.
Some accounts of this are recorded in early 20th century folklore collections. According to some informants, black cat bones were used in this time and place (the 1930s) to rid oneself of troubles, as lucky pieces, to cause sickness to visit an entire community, and by a jealous lover to get his or her lover back from a rival. The cat bone is said to “enable you to marry your choice,” “bring you good luck all your life,” “will fix you so that you can do anything.” ( mostly p. 156). But you usually have to boil the poor thing.
One informant says, though, that even if you find a dead black cat in the woods, its bones are stil powerful magic. I think that some of the uses of the black cat bone that I learned in the early 90s in central Alabama have some roots in these developments of the black cat bone traditions, somewhat different from those of the European grimoires.
This usage involved making a necklace of a ritually prepared (and, unfortunately, ritually killed) black cat bones. (Yes, I know how to do it, and no, I’m not telling you. I’m not going to be responsible for another string of black cat abductions adn killings like any cat owner living in the outskirts of Birmingham in the early 90s can tell you about.) This necklace conferred occult power to the wearer, particularly for travel in the spirit world (called “dreamwalking”) and for protection against psychic attack. It was standard “getting ready to do work” garb for those who wore it, and considered a source (and symbol) of power that was worth guarding ferociously. This group used the leg bones of black cats for this purpose (not any other bones).
So, my uses of the black cat bone are informed by a few diverse strains of folk belief and recorded practice, as well as my time in central Alabama as a participant in and collector of the eclectic magickal practices of those black cat bone folks. This is also why I collect and sell the leg bones of black cats (and I collect them without the use of violence, by the way). In theory, according to most of the lore, the power bone has to be discovered by a process of trial and error — the special bone will make itself known to you in the de-catting process. My use of the leg bones as ritually powerful items is shaped by my time and experience working with this stuff in central Alabama. So now you know what’s not quite traditional about some of my uses of the black cat bone.
Great, you think. I don’t care about all that crap. I don’t care WHY you use a black cat bone to return a lover, and I don’t care why you say it doesn’t have to be boiled in order to work. I just want to know how to use it.
Fine. Here’s what I recommend. Either build a reconciliation altar around it, or else have it as the key ingredient in a mojo bag. In either case, dress it with Van Van oil (the Mrs. Dash of hoodoo condition oils), or else a Come to Me and/or Reconciliation oil. There are a number of different reconciliation spells you can use in conjunction with this. I would incorporate name papers and herbs as well for a mojo bag, and candle burning for an altar. Like any ritual item of this nature, keep it where other people won’t mess with it.
 Piseog is Gaelic for black magic, sorcery, an evil spell, or an incantation, depending on which dictionary you use.
 A post on this will follow. For now, see the following list of links for your reading enjoyment
Magic Spells from the Book of Saint Cyprian Antigo Livro de São Cipriano, 1993, Editora Espiritualista, Ltda, Rio de Janeiro, Translated by Ray Vogensen
Cat Yronwode at Lucky Mojo on the Black Cat Bone
[n.b. Cat’s page suggests that Hurston’s account of getting the cat bone involves returning a lost lover. I believe this to be an error; In Of Mules and Men, Hurston says the Frizzly Rooster (a root doctor) told her she needed it so she could move secretly and invisibly sometimes in her conjure work.]
 See The Frank C Brown Collection of NC Folklore, by Wayland Debs Hand and Frank C. Brown. Duke University Press, 1964.