Get dimension id of another mod?

Hey modders I have one mod that just adds a custom dimension you spawn in when the world is created and another separate mod with an item that teleports you temporarily to the nether before putting you back where you were. How can i teleport the player back to this custom dimension, or get that dimension id for the dimension id object block tot teleport, without combining the mods? ideally id like a button upon creating the world that chooses either custom dimension or regular world so you can choose but that seems beyond me right now, Thanks!