I don't know about hammers, but I do have a key board and access to the DSM IV manual via the Internet. The criteria I listed come straight from the DSM IV discussion of NPD. I also have a stick of dynamite!
However, Wolf is correct. Only a trained professional is qualified to diagnose someone with ANYTHING! If you feel that your sister is experiencing severe emotional or life difficulties, the best thing you can do for her is to encourage her to get some professional help.