I finally have my copy of NO$GBA, but for the life of me, I can't figure out one important thing: how the hell do I get "Assemble File" to assemble code into a pre-existing ROM? If it's at all possible?

I tried the ".norewrite" option in my ASM code, but the org directive still gets ignored and everything compiles at the beginning of the ROM, destroying the header and corrupting the file.

Goldroad follows org directives, but it doesn't seem to have a .norewrite like NO$GBA: the code compiles to the right place, but the end result is a ROM that's blank except for my code.

Am I missing something?

I thought NO$GBA wouldn't let you compile directly to a ROM...

Perhaps take that assembler that outputs at the correct position in a blank file, and then use a data copying program (I made one called Data Mover, and I think somebody else made a similar program recently) to copy that over to the real file?
(I just remember I didn't bother to support command-line arguments in my program)
Though I suppose that might be annoying to use two programs for every change.