Check out Brownells gunsmithing catalog-- For a start see:
[ http://tinyurl.com/8q77x ]
This is just a single groove riffler. I just searched "checkering"
you will come up with pages and pages you won't want but there are
some stock checkering tools that will layout 2 or 3 grooves. These
may work for you as some of the particularly fine English guns
used as fine as 32 lines per inch.
I have an old paper catalog here someplace that I saw a few days
ago. It should turn up when I stop looking.