Use
this to disassemble your clients. It makes disassembling clients easy. Explaining how to hack clients would take awhile but basically you get a new client and an old unhacked client from a mod selector. Name them both client.swf and disassemble them with rabcdasm or that tool I linked. Each time you'll get a folder named client-1. Put the client-1 from the new client in a folder named "new" and put the client-1 from the old client in a folder named "old".
Then you go into the mods folder of a mod selector, open a hack folder then open a txt file with a version number using notepad++ and look at the top. You'll see stuff like
#set charMaxHp "_-06W". Use a program like astrogrep to search in old\client-1 for _-06W. Open the class you found _-06W in with notepad++ then find a unique piece of code somewhere that only shows up in the class you found _-06W. Now search for that unique code or word in new\client-1 and you'll find the same class as in old\client-1.
Now all you do is see where _-06W is in the old class and compare until you see what it's called in the new class. You do this for all
#set things at the top. You can compare the code side by side if it helps to find the same spot. Line numbers in the xml file you find in mod folders also need updating. You look where the code is added in the old client and go to that same spot in the new client and update the line number.
All of this might not make sense right now but there are tutorials scattered around the forum that could help you understand it better.
It'll start to make sense when you try it for yourself.