When I replaced the top on the wife's TR6, repaired the tonneau snaps,
and installed the boot stick cover, which required the snaps, I used
the VTR site for basic info.
I went to a local leathercraft shop with some of the old parts, bought
a "kit" with all the snap pieces needed, and the tool required. The
owner showed me how to put 'em together and use the tool properly.
One afternoon, all three pieces done, they all work fine, not hard at all.
Make sure you get a piece of scrap leather for a working surface, it helps.