There are no easy way to get a Fuse character onto the Unreal skeleton. You have to export the Fuse model as a OBJ without skin weight then manually skin/rig the character yourself inside of Maya/Blender. This takes a lot of time.
The question is why would you want to change from the default Mixamo skeleton to Unreal skeleton? The Mixamo skeleton works just fine in Unreal Engine 4 if you use inplace animation. All the face morph works too at least when I tested it out.