You can try literally soaking, by rigging up a pan under the drum panel, or by removing the panel and soaking it overnight in a pan of PJ Blaster or liquid wrench. Regular oil probably won't cut it and neither will WD-40 if its really stuck. If you have buggered it up, you will need to find another panel and Ebay comes to mind as a source.
Removing the panel requires that not only the axle be removed, which is reletively easy, but the bearing and its carrier will need to be removed too and this requires a big socket, 1 7/8 I think, and either a slide hammer or a homemade puller, unless the bearing is a slip fit on the axle housing, which is unlikely.
-Michael