FFF power or Pistol powder works best with sidelocks
Cap Covers seal your #11 caps in foul weather
RWS Dynamit Nobel 1075s #11 caps (round red box) are the best
Buy a hotter nipple (I think Lyman uses the 6X75 Italian size)
Get a round flash guard to fit over the nipple
Get a nipple remover. I prefer the one that removes both musket & #11s.
You need a wedge pin remover. They are fork-shaped.
Must have sling & sling hardware. Those Lymans are heavy rifles.

Most of this stuff you can purchase under "Blackpowder Accessories" at Cabelas.com