Hi there and welcome!
I have only ever used the LEM's Jalapeno Bacon Cure seasoning.
I don't have an answer for the amount of Jalapeno powder you need to add but I can tell you that my experience is that you add all the seasoning with the cure and it makes its way into the meat plenty even after rinsing (using the LEM pack).
Now please please please head this next advise!
At the very least, wear a mask or a bandanna or something to cover your nose and mouth. When you get to pouring higher amounts of pepper powder on stuff and tossing it around it WILL get in the air and you WILL breathe it in. This will cause sneezing, burning, and snot slobber like you may have never experienced LOL. Just cover up and you are ok
Oh, I would also highly recommend a pair of goggles or some kind of decent glasses as well :)
Best of luck and let us know how it comes out! :)