The oil glands and castor on beaver are simple to remove and should be done so prior to gutting. Just grab them and cut well under them down to the bone from the top of the pelvic bone to the top of the tail.
The second thing that is often over looked if you look at a skinned beaver up by the neck on the belly side you will see a large amount of meat that is actually its siliva glands they are light pink in color when compared to the dark red meat. These are not tastey and should also be removed. Other then that the rest is like any other small game critter gut it out keep it clean and enjoy it. We crock potted half a sm one yesterday while hauling wood my wife and I sat down and ate most of it up when the days work was done.