Create the person as a child of yourself and then detach the profile from you. Make sure you "follow" it so you don't lose it. If you need help, let one of us know. Also, if the person has been dead for a hundred years, are you sure that he/she is not already in the tree? I can do an Advanced Search for you if you want first.
http://www.geni.com/account_settings/recent_activity
you can change what you want people to see you doing here