A box is about the worst possible case for vertex arrays since you've got plenty of shared vertices but no shared normals. The only way to do it is to duplicate your vertices so you end up with 4 vertices and 4 associated normals for each face. Theres no pointer magic you can do to get around this, since GL will just read the data in in continuous blocks.

It would be nice to have separate indices for vertex, normal, texture coords etc. but I don't think that'd be as hardware friendly for caching. Plus you'd have so many more indices the actual data to move around would greatly increase.