Hi M.,
I actually didn't use a doll, but at the time I was training my daughter (she was 18 months old), she LOVED Elmo. I had a stuffed Elmo doll, and I would put Elmo on the little kids potty on the floor that sat in front of the adult potty. Using a child's potty seat for the adult potty, I would set my daughter on the adult potty while telling her that Elmos is going "potty" on the child's potty. She loved it, and it worked. So I don't think you have to use a doll, necessarily. Perhaps use a stuffed animal or get a stuffed character that your daughter loves. It will likely mean more to her.
Good luck and if you have any questions, let me know. Both my children (a boy and a girl) were trained before they were 2 years old).
A.