Martylum mentions that brake linings can be ruined by being soaked in gear oil. This is true. However, there is a way of salvaging most brake linings (and also clutch disc facings) soaked with any type of oil or brake fluid.
Please don't try this in an enclosed space, and don't breathe the fumes!
Use laquer thinner and soak the affected part(s) thoroughly.
When they are quite well soaked use an oxy-acetylene torch to heat the part, but don't get it too hot. The oil, diluted by the thinner, will boil off and burn. If the shoe is really badly soaked, and has been for a long time, you may have to repeat the process one or two additional times.
If you have not thoroughly removed the oil from the lining, the worst that will happen is that oil will retun to the surface when the brakes have been applied hard and long enough to heat them up - probably to a temperature greater that you got them to in the fist place. If this happens, remove the shoe and repeat the soak and heat process. Over the years, I have found this a virtually sure-fire way to restore oil-soaked friction surfaces.
Brian