Now with the HBC supporting args I hoped to have some emus load straight into a specific rom, but after days of reading and trying I can't get anything even close to this myself.

So I did what you should do, I googled and found 2 emus that have been modded to do this.

SOURCES
GameBoy --> [www.mediafire.com] and Snes --> [www.mediafire.com] (btw both of these are older versions and the snes black screens when you quit)

I had a quick look through the sources and see some changes, but tbh am outta my league on this.

So I thought I'd ask around to see if anyone knows of any other emus that either support direct game loading using args with the new HBC, or if anyone can be bothered some pointers as to what to change in sources to allow this for other emus EG N64, sega emus, neo geo etc.

I hope to learn from this and am not expecting anyone to do it all for me (although that would be nice).

By my understanding arguments are stored in variables called argv[0], argv[1] etc.

Find the main() of the app you want to modify, and add some code to detect if whatever argument the ROM is exists (I think its argv[1], and argv[0] is the path of the loaded DOL, but I could be wrong).

So something like this I think:

if(argv[1])
{
  ...code here...
}

the "...code here..." part should be to call the emulator's ROM loading function (look through the source, maybe you can find it), passing it argv[1] as the ROM path

Beyond this, I don't know anything more. I'm not at all experienced in programming, and some of what I said may be slightly inaccurate. I hope this helps at least a little.