Donload the AR freezer ROM and run it in WinUAE... that has a special mode for detecting the decrementing opcodes... it really does work... well I have a Real Action Replay III here and that works, but the Software one should be nearly as good

-Edit- Reading ASM code is not easy, you need to have a good mental map of the Amiga's hardware registers to follow whats happening and where... It is hard enough when you write the code yourself, and reading Disassembled machine code is an art that I find VERY difficult...