I really like the way that looks...and I'm really Dremel tool challenged and your method looks like something I might be able to do!
You just filed the hook slot at the bottom of the mold a tiny bit wider to fit the wire? Any other change?
Yes, only a few strokes of a very fine file... basically, you are creating a tiny triangle behind the hook for the keeper wire, and you need half of the triangle on each side of the mold. When you are done, it should have the shape somewhat like a sideways ice cream cone when viewed from the bottom, and the cone (space for keeper wire) should be smaller than the ice cream (hook slot).
Although Tom brings a valid thought, I leave my wire straight and I've never had a keeper wire pull out in however many years I've been doing it... maybe it's because I'm using galvanized wire which it isn't as slick/smooth as stainless... the plastic is still the weakest link and tears with less effort than it would take to pull the wire out.
No other changes associated with the keeper... however you may have noticed that I ground and area below the 1/8oz to allow for a bigger hook with certain applications.