You can get that type of insert at woodworking supply stores, http://www.woodcraft.com/family.aspx?familyid=1048 for example. Our just use blind nuts which are available through hobby shops or local home centers.

Better yet, do it the way the kit suggests. I assume you are referring to wing hold down bolts, your post was not completely clear. Tapped wood blocks strenthened with CA with nylon bolts work great. Tough I have no experience with Pete N Poke, I have never had one fail on any plane that I have built.

Mike