I had the same problem with these tires, trying to stretch them onto my Mavic Ellipses (deep profile rims).
I don't know if there's any secret to it, but the instructions clearly state that you should NOT use tire levers. I just used a lot of brute force, and full-finger gloves to keep from rubbing-off the skin of my palms and thumbs. It seems impossible, but they will go on, eventually.
I've found the best way to mount these tires is to squat down on your haunches, clamp the rim between your thighs and upper arms, and work the last several inches of bead over the rim little-by-little.
If it's any consolation, they will stretch once they're installed, so future removal and installation will be a snap.
By the way, the ride quality of these tires is superb -- well worth the effort of installing them.
Good luck.