The Chimney cap on my chimney is secured with sheet metal screws. I
have a piece of flat steel with a hole in it and a flange. the liner
comes through the hole and the cap is attached to the liner with
screws. The flat metal piece is actually just caulked to the original
chimney flu. All supplies were bought from the wood stove store where I
bought the stove.
Once a year I remove the cap and clean the flexible SS liner. I have
one of those stiff brushes with a piece of rope tied to each end. My
son pulls one piece of rope through the wood stove which pulls the
brush down the liner and then I (standing on the roof) pull the other
piece to pull the brush back up. We repeat this a few times, then
replace the cap and I'm done.