It's easy to convert a TC Hawken or Renegade from flint to cap, but not from cap to flint. The reason is a caplock barrel is breeched with a snailed breech. There have been people mill and weld, in order to convert, but it doesn't look practical or, look right.
Swaping the locks, should not be any problem. Not every lock is exactly perfect, but are usally pretty close. And, even very from one rifle to another, from the factory.
However, the barrel is a different story. You have two choices, buy a breech plug from someplace like Track of the Wolf, and hope you can unscrew the factory one. Then you'll have to fit and bend the tang to fit the stock, drill the tang hole, fit the breech plug to the original barrel, finish it to closly match the original finish, locate and drill and tap the flash hole in the appropriate location, and install a liner.
The other option would be to buy a used TC flintlock barrel and lock and put them in your stock.