It took me 6 months to get my grey to take a bath. In the mean time she was misted. I would put a bowl of water in the cage with some veggies in it that would sink. I did this in the mornings for about 30 min before the first feeding. She would have to get wet to get to the veggies.
Now she well jump into a bowl with no problems and get a bath.
I dont like the idea of forcing a bird to do anything.