We have different axle setup than you, but... most likely you will have to remove the brake drum. There are a couple of front axle sensors that I have changed without taking the wheel off. They just pull out. There is a spring clip/bushing that holds tension on them to prevent them from moving once they are set.
If you can get good access to the back of it and can pull it out, you won't need to take the drum off. To adjust them, you simply shove them in until they contact the tone ring and they are set to go.
Good Luck!
Doug