Hmmm, my attention was drawn to this thread by the title.
I am an attempted Shaman (no joke :P I'm being taught, if you think its a joke, well I can understand that :) But i'm young and not the best one for advice )
It is possible for a physical change, however, your body must be aware of it. It took me a while to learn how to even change my hands, I am not yet possible of a body change, but if you are extremely wanting advice. The best you can do to even start of, is to think very, very hard about the animal you would want to become (I used a female deer, doe, to start off with). Pictures can be used in the aid. But keep in mind, it may take a long time to start having even the slightest morph.
Bascially try a sense change for the start. If you live in the area of the animal you want to become, you can try and be as one with it. Try and feel what its feeling and imagine what its doing. When you get good at that, you can sometimes hear what it hears, smell what it smells, (as well as seeing) and feel what it touches.
You may want to contact a shaman for further detail :)