@Gooblah: alright

(one more vote folks). I really don't know how its done normally. Because normally it's a square flag. And I'm not 100% sure you fix it by stretching. Maybe, but I don't know. The way I do it is I have a template (from the horizontal flag modification). There is a space for the picture, and black bordering it above and below.
Here are the flag graphics. I will include both teotihuacan flags, though I suspect your vote may be pretty accurate. They are in a word document. I am guessing we don't want the border. So simply click on the flag you are making, choose "no line" on your drawing toolbar, and then copy. EDIT: actually, if you want the borders, you're welcome to omit the "no line" step. Just make sure they're all bordered or borderless. If you choose to keep the borders make sure it gets aligned really carefully. Otherwise we get what I call the "using a scissor to cut an outlined image" effect.
Then, you open my template flag (which is aztec.dds for you), you paste the image, and resize/move the image so that it covers the old image exactly.
Then you use DDS Converter 2 or similar program. Anyways, it's almost as simple, I guess. But I have a feeling you have to do it my way- I think the black above and below is there for a reason.
The template flag and the word document containing all the flag graphics are attached.
EDIT: I have already done Aztec, Cherokee, Chimu, Creek, Huron, Inca, Iroquois, Maya, Mixtec, Olmec, Shawnee, Sioux, Toltec, Zapotec. Please omit these flags. So really, there aren't a lot left to do. And also, the modern and colonial civs will not be needed for quite a while. So the only ones needed right now are Arawak, Carib, Miskito, Nazca, Tarascan Teotihuacan, Tupi. Though you are welcome to work ahead on modern/colonial flags, as they are finalized.
thank you
@Moopoo: sorry about the wait for the settlermaps. I will prepare that as soon as I've handed in my essay on wednsday (more or less)
Gooblah, I also now have duplicates for Tarascan and Nazca. Take your pick.
(By the way some of the flags are just plain brilliant!)