Brett......they are normally held in as John described above. You don't need a head on the nail. I make mine out of small brads. Put them into a lathe, or an electric drill and file them to a long taper, similar to an old, old phonograph needle.
I normally inlet an inlay, glue it in with an epoxy, then drill a small hole wherever you want them to be. The hole should
be slightly smaller than the large end of the tapered nail. Them drive it into the wood until it becomes snug in the inlay,
then clip it off and file smooth with the inlay. When you drive the nail into the wood, don't get carried away here, stop
when it gets snug in the hole, otherwise you will pull a dimple into the inlay, requiring a lot of extra filing to remove it............................Don