You can get the wireforms you mentioned at O’Hare spring http://www.oharespring.com/fishing.htm.  The item number is #340.  Item #340-800 is one I designed and is used on my Molly baits; it gives a little more length for holding power.  I’m not sure of your plans, but I would be leery of just bonding them into balsa, they will likely fail.  The plastic baits can get away with it because they are more dense and mold a hard plastic skin layer around the forms.  I’m working on a couple of new baits that are going to have a density halfway between balsa and cedar and I’m using a complete through wire construction because figure 8 inserts would not be strong enough.  Perhaps you could “thread” them together somehow, but I think making a complete form would be easier.