Like everyone else has already stated, there are different laws from state to state. If you pick up a copy of massage magazine or massage and bodywork they usually have state by state regulations in the back of the magazine. I believe most states require approximately 500 hours of education. This is divided between A&P, pathology, kinesiology (may be very different than other kinesiology courses at a university), business, ethics, awareness, communication, and bodywork classes (these will vary from school to school). I would advise you to find a school that is COMPTA accredited. I teach at a school in WV. We have programs offering 700+ hours as well as an associates degree after taking a couple of semesters of classes at Marshall University.
There are a couple of states requiring as much as 1,000 hours. So make sure the program you choose meets the requirements for practicing in your state.
Some programs may accept your A&P classes from your BSN program, but I would advise you to take the A&P offered in massage school as well. It tends to be a little different than A&P for nursing. The focus is more heavily placed on the muskuloskeletal and fascial systems of the body. These aren't given as much attention in nursing A&P classes. If you opt out of them, then I would recommend reading A Trail Guide to the Body and Anatomy Trains. They would probably make up for any discrepencies between the classes.
Check out these organizations: Associated Bodywork and Massage Professionals, American Massage Therapy Association, and NCBTMB. The last is the organization which offers the "national" exam.
Read up on the different types of massage, and recieve as many of them as possible before you decide which school you would like to go to. Find a school which focuses on the modality you are most interested in. Some modalities may not be covered in a basic massage program. Most programs cover Swedish massage, Deep Tissue massage, and then have classes meant to expose you to other modalities. It may take more extensive study to become a practitioner in these other modalities though. ex. Shiatsu, Thai Yoga Massage, Neuromuscular Therapy, Polarity Therapy, Hot Stone Massage, etc...
There are many different types of massage out there, and I am yet to find one I don't enjoy. Check out massagetherapy.com
Good luck to ya!