Like Shoshanna said, the character needs a trait that the readers can sympathize with. I wouldn't call it a redeeming characteristic, because that implies that he might become a hero instead of remaining an evil protagonist, but there has to be something that makes the reader identify with the villain. Actually, the part of the premise is something we can all identify with - fighting against aging. If you keep that as a central goal of his, it will go a long way towards making the story work. After all, we may not agree with his methods, but deep down, can we truly say that we wouldn't do the same in his place?