You have to remove the rear cover of the differential and drain the oil. Then remove the pin that holds the spider gears in place and remove the spider gears. A small bolt holds the pin in place. Then you have to push the axles in a little to remove the c-clips on the ends of the axles that hold the axle gears on and then pull the axles completely out of the rear. The seal can be pried from the axle housing with a screwdriver. the bearing may have to be pulled out with a bearing puller.
What makes you think you need new bearings? Are they noisy? You will be able to inspect them with the axles out. If you just have a leak, seals should be all you need to replace.
You shouldn't have to remove the spider gears.... They will stay in place long enough for you to remove the axles. After you remove the axles, put the pin back in place so they don't come out... It'll be a PITA to get them back in I hear...
They're not too bad to do. I did one on my truck when I saw the seal leaking. Figured I might as well replace the bearing too. Take your time and be sure to rent / buy or borrow a bearing puller or slide hammer to get the bearing out.