+1 on stapfan's comment. Get a couple on Bontrager tire levers. They are lightweight and will not distort, even when putting on a difficult tire.
http://bontrager.com/model/07799
Another trick that a Mavic "racer chaser" shared with me is to use a light spray of Windex on the last 6-8" between the rim and tire. You can roll even the toughest tires on with the palm of your hands. If you can't, a single tire lever will do the trick.