A Do It Yourself Guide (Seleucids & Romans), please?

[GodEmperorLeto]

I've been trying to figure out how to fix the Seleucid and Roman flags and voices myself, but I just can't seem to figure it out. Does this require coding? Or can it be done with a simple .txt editor? I know tons of people are bitching about it and it can get annoying for the modders to hear about it 20 times a week, but if anyone knows how it can be done, it might be worthwhile to post simple guide (so long as it isn't too confusing and difficult for a layman to do).

If it can't be done, that's cool. I can wait for the final version. But I've been itching to figure it out and do it for myself, and I wouldn't be too surprised if it wasn't something I couldn't do without coding.