It is not a trivial undertaking but doable. If you have a set of chisels, a couple gouges, rasps, a vise, pistol drill, drill set, countersinks, saw etc. and if you plan to do the barrel channel and ramrod groove you will need several additional tools. If you are only interested in one gun, in my opinion it is not worth the investment in tools. You would be money ahead to look at a kibler southern gun and see if he will leave the buttplate inlet out of the gun. If you have the tools and the desire to build your own gun, forget everything I said. This forum is the best resource that you will find.
Blessings, Bill