How to replace HO52 axle seals?

[Stocker]

While cleaning up my wheels (topic for another post), I found one drum covered with oil, so I need to find out if I can replace the seal or farm the work out. I have basic hand tools and a concrete driveway, but not a lot of time - and the weather's been a bit dicey lately. What needs to be done, and how difficult is it? As always, thanks for the advice!