I have researched this fairly deeply, as the natural treatments for MS are similar to those for Rheumatiod Arthritis, which my wife has treated naturally all the way into remission.
Natural time in sunlight, gentle exercise, a healthy diet, and supplemental Vitamin D are all good.
All of the suggestions in my Hub: Heal Yourself: The Most Effective Treatments for Rheumatoid Arthritis are also effective for MS.
I have heard of two stories of complete remission from MS through natural methods. One is from Richard Bolles, the author of What Color is Your Parachute. It is in another book of his, The Three Boxes of Life and How to Get Out of Them. In this case, nothing more than an attitude change and focused exercise led to a woman going from being almost totally paralyzed (quadreplegic, able to move just two fingers) to complete remission in a few months.
The other is from Machaelle Small-Wright at www.Perelandra-ltd.com. Her system of flower essences and the MAP approach to healing was used by a woman with MS to achieve complete remission.