Since it is such a nice, big plant, and since it is in a plastic pot, here is what I would do.
1. soak the entire root mass and plastic pot in water for 15 - 20 minutes.
2. take a utility knife and cut the plastic pot into several large pieces so to remove the plant from the container
3. Pull apart gently the orchid letting it divide naturally.
4. pot it up in a basket or baskets with a new moisture retaining mix.
Hope that helps!