Back in my day I used to use a program called Win32dasm or something, it disassembles anything down to its machine assembly code.
It was when I was like 13 though so I don't know if its still around/if it works, back in those days I used it to find the parts of programs that tested for a registration key then I opened up the program in a HEX editor and I would change it and bypass the registration.
I've only gotten dumber since then
