You really don't want to force anyone into the show. It's a bad thing plus he'll probably get so fed up with your insistence that he'll never watch it.
But if you do want to "convert" him, just show him the awesome side of the community, you know, the music, the art and maybe throw in one or two of the references the show has. Then, let him watch one of the cool episodes. That's how I did it atleast, and my friend is now a happy brony (Well, maybe it was easier for me because he wasn't a hater).