Yes, everything I wrote after the first batch of code is an explanation/analysis of said code. And yes, you can choose which items to open up to Wizard Slayers simply by removing the items I selected (Belt of Intertial Barrier and a bunch of Cloaks) and writing in a bunch of different items to take their place. There is no limit (that I know of) to the number of items that can be placed in a single COPY_EXISTING.
But let me ask you this: Do you just want to correct the default Wizard Slayer's ridiculous item restrictions, or do you actually want to write mods? If you just want to make the one change on your home system, then sure, the best thing to do would be to take the code I posted above, swap the items around, run it on your PC and be happy with a Wizard Slayer that can actually wear Kaligun's Amulet of Magic Resistance. But if you want to actually become a
modder, there is an ancient, sacred ritual through which all coders must pass if they hope to reach the hallowed status of
modder: You crack open the TP2s of other mods, and steal their code. Sure, you'll also have to study README-WeiDU.html in order to understand what the hell you're doing, and copy down various Tutorials for even greater insight, but basically it all boils down to stealing other people's code. That Wizard Slayer fragment I posted? Based off a chunk I tore out of Ashes of Embers. But I couldn't call it
my code until I understood why every little piece of it did what it did. So once Version 2 of my Kitpack comes out (around the turn of the year, I think), you'll be able to see what I do with the Wizard Slayer, and hopefully by then you'll be able to read the code and understand what it all does. And hack it apart and use the pieces to help you construct mods of your own.