There are 3 relevant lines in the player.entity GameInfo file:
hudSkinData
     loadScreenCharacterBrush "LoadScreenCharacterFourth"

and the last two lines:
playerThemeGroupName "PlayerFourth"
playerPictureGroupName "PlayerFourth"

I must assume that these relate to the following files in the Window folder:
LoadScreen.brushes
PlayerFourth.playerPictures
PlayerFourth.playerThemes

which in turn relate to the textures:
Startup_Loadscreen0_MOD.dds
Player_Portrait_Large_MOD.tga
Player_Portrait_Small_MOD.tga
Player_Portrait_Window_MOD.tga
Player_Portrait_Button_MOD.tga
RaceLogos_MOD.tga

Now... The LoadScreen and playerPictures file and textures, once modified, work just fine. However, I keep failing to make a new .playerThemes file for the new race. Even if all I do is copy PlayerTech.playerThemes and rename it (letting it still point to the default RaceLogos.tga texture), all I get for icons are solid color boxes. Actually going all the way, making the new RaceLogos_MOD.tga, and pointing PlayerFourth.playerThemes at that does not work either.
Has anyone successfully used an additional texture for playerThemes? How does one do it?