Hi Deja
I presume you don't want to go cold turkey?
Ann Richardson suggests to do gradual weaning by slowly cutting out one feeding per day by replacing with milk (rice milk I guess in your case). She suggests to start with the lunchtime feeding. Once you have succesfully replaced this meal never give this meal again using breast feeding. If you are experiencing engorgement, only express enough milk to relieve discomfort otherwise you will continue to stimulate milk production. She suggests to use arnica cream and cold compress/cabbage leaves to use for discomfort. After 3 days (or longer if you wish) start replacing another meal, the morning or evening meal. You can even still continue to give one feeding for a long time still should you still wish to give one feeding per day only. But I guess you wouldn't want to do that because of the milk allergy.
I have never tried it, so please let us know if it worked!!
Does he use a dummy or any other soft toy/blanket for comfort? I think he is going to need a little extra something since the weaning is often very emotional for them (and the mother).