You want to port an AMX Mod X plugin to a custom module? It's highly unlikely that a tutorial could even be created to account for the millions of possible situations that would require a different approach.
Learn how to create a module first and then search for how to implement the features you want (that's probably the best that's going to happen).
99.9% of the time, doing this is going to be unnecessary.
Further questions about creating modules should be posted in the modules subforum.