It's probably not very hard, depending on your skill level and experience.
Here's how it's done: Safely jack and support the vehicle on proper stands and remove the rear wheels. Remove the bolts securing the axle drive flanges to the bearing hubs and remove the axles. Remove the adjuster nut and outer rear wheel bearing. Continue by removing the brake drum/bearing hub assembly. Then remove the inner wheel bearing, you may need a puller or chisel and punch to remove it. The inner races will have to be pressed or driven out and new ones pressed or driven in.
Lube the wheel bearings with the appropriate grease and reassemble with a new seal. You'll need someone who knows how to show you how to adjust the wheel bearing if you don't, but remember it's kinda critical so it needs to be done right. It's a good time to check the rear axle lube when it's all reassembled.