6. Delete all of the new bones on your imported polygons that don't affect them. You can tell if a bone affects it by rotating the bone in the viewer. If nothing moves (AND it is one of your new bones), delete it!
I don't really get this step... are there supposed to be new bones? I'm importing parts of a model rigged to Ike to another Ike model, so they are matching bonesets. Does this still apply?
If someone got this to work, there are some steps that could be made more clear if a video tutorial was made!