If he is still competent to make decisions for himself, then you have to wait for an emergency that will send him to the hospital and then to the nursing home. That sounds horrible, but many others here have said the same thing to those with your very question. If he's not competent, then I believe that you can just move him with a doctor's order for going to a nursing home as his medical POA.
My mom refused to go until she had an accident at home which put her in the hospital and sent her to the nursing home.
My mom refused to go until she had an accident at home which put her in the hospital and sent her to the nursing home.