Anyhoo.. Short and sweet. A resoure that may or may not be of interest to the spiritually inclined amongst furries is a book called "The Art of Shapeshifting" by Ted Andrews, ISBN 1-888767-32-4, and you can get a sneak peek at
The book's got a dozen excercises, and while the book doesn't teach zoomorphing (no surprise there), he does cover auric shapeshifing, dream shifting and personification which looks like a form of invocation... Which, yes, is a gross generalization.
Anyways, if this is of use or interest to folks, great, if not, feel free to ignore this.
Abaddon / Apotheosiswolf