Hows that 'guide'thingy coming along? Doesn't have to be anything too elaborate. Just a decent enough outline to see what has been done and what needs to be done next. If you are stuck then just make it as specific as you are able then we will break it all down later.

As for the prt0.as and crt0.as is the one we are using now insufficient? I know that it's supposed to be a sort of hack, but will it not direct the linker to make a proper GBA ROM?