Initial PreparationYou'll need the
DDS Plugin and
Normal Map Plugin for GIMP.
Firstly, if you haven't done so already, unpack the "textures" .bsa, ideally to somewhere else, using
BSA Commander or such. If it's not in a Textures folder already, (I can't recall) put it in a folder labeled Textures. Go to Characters, and create a new folder named (for the purposes of this tutorial) Mystmer. Next up, open Characters/Imperial. Imperials, Bretons, and Nords have no texture files unique from one-another, and it sounds like yours will be similar in most ways as well. You should see textures for their head, ears, teeth, etc, but most of the folder is taken up by "age" textures like headhumanf20.dds. Open one of these "Age" ones up in GIMP, and you'll see it looks a bit weird. Almost monochrome, with the type of detail suggesting someone sticking their face into a very detailed mold. The contents of these are "pasted" on the race's head at the listed ages. They don't need to be multiples of 10, but if they're not, they'll only work for that exact age. For example, if the list went...
headhumanf10
headhumanf20
headhumanf33
headhumanf40
...Female NPCs of the race from ages 10 to 19 would have headhumanf10 added, ages 20-39, excluding 33, would have headhumanf20, ages 33 would have headhumanf33, and ages 40+ would have headhumanf40. Traditionally, this is done to add wrinkles as an NPC grows older. However, since we want the gem on the forehead to change color depending on the age, we have to use these textures instead of plain old HeadHuman. Besides, that way the gems might get wrinkles. Copy the textures for ages 10-30, as well as their normal maps, to Characters/Mystmer. (That is to say, headhumanm10, headhumanm10_n, etc) To save some menial work later, rename the ones for age 30 to age 50, and the ones from age 20 to age 30.
Most races have a six-part system for this, changing the wrinkles every 10 years until age 60. Since we want six different colors for the gems, this would work fine, except they're not supposed to age very much. This is why we copied only the ones for ages 10-30 over. Copy the age 10 ones again and change the copies to age 20, copy the age 30 ones and change the copies to age 40, and copy the age 50 ones and change the copies to age 60. Now we have a six-part aging system, but they'll never look older than a thirty-year-old from another race.
The EarsAre you absolutely sure High Elf-ears wouldn't work? They're bigger than Dark Elf ears and bent back... It would save you a sizable amount of trouble. If they would work, you can skip the remainder of this section. If not, you'll need to install the
NIF Importing Scripts for Blender. Then, go to Meshes/Characters and create another Mystmer folder. Next up, open HighElf and copy earshighelf.egm and earshighelf.egt to your Mystmer meshes folder. Open Blender. If your version starts you with a cube in the middle, press the delete key and get rid of it. Then select File/Import, and choose NetImmerse/Gamebryo (.nif) from the list. Select EarsHighElf.nif, which should be in Meshes/Characters, and then click "Import". They should already be selected; if they are, they'll have a pink border around then. If not, just press A.
Since the changes are relatively basic, there are only two functions we need to concentrate on: Scale, and Rotate. To scale, press the S key and move the mouse to determine how much it's enlarged or shrunk. To rotate, press the R key. However, you probably won't want to scale/rotate them on every axis. While scaling/rotating, press X, Y, or Z to alter them only along that axis, or hold Shift while pressing X, Y, or Z to alter them on both axes
aside from that one. Once you're done, select File/Export, and put it in your Meshes/Characters/Mystmer folder.
I use Photoshop, so can't teach you how to use GIMP. Draw your gems of the appropriate color on the foreheads of the "age" .dds files, and just remember to make sure the Normal Map Filter is suitably exaggerated for the Normal Maps. Eyes can come later, but rest assured that they're significantly easier. Aside from the glowing, which I'm not quite sure how to do. NifSkope is a nightmare.