You can give your BP a bath soak. Just fill a container/bathtub with warm water and stick your snake in there for 30 minutes. Just make sure the water doesn't get too cold. You can do this daily untill you think the mites are gone.
I've heard vegetable/olive oil works well. I've never tried this method, but it's suppose to suffocate the mites when you rub this on the snake itself.
Also change it's substrate to paper towels during treatment. It's easier to spot the mites on white, than on news paper or bark substances.
I personally like using Provent-a-mite. It's a spray that you can only buy online. It works MAGIC. After the first treatment, most if not all mites disappear. It's a product that you just spray the tank/tub with, not the animal itself. You just have to be careful with the instructions. The spray is dangerous to the snake as long as it's still wet and/or have vapor. Its harmless dry.