Now that I have built an 1840s banjo, I am in the early planning stages of building an 1850s banjo--a reproduction Ashborn. I'm actually thinking about making two of them at the same time. One with the patented 1852 tuners and one with a slotted peghead and machine tuners to be used for alternative tunings for playing clawhammer.
Keep us updated. Building a minstrel banjo is great fun!
They are held in place with a single brass nail. My method follows George Wunderlich's method (which he explained on an episode of the Woodwright's Shop with Roy Underhill a few years ago--and that one episode is what got me started down this path in the first place) which is what he thinks Boucher actually did.
1) Punch a dimple into the bracket with an awl (you can see my awl in the photo--it is one of my prized tools)
2) Run a file across the dimple until a hole opens up--just a few swipes will do it
3) Nail it into place
Mine are very inartfully clinched into place (as you can see in this picture). I will do this better on future banjos.