I've just been looking around through the xml and python files so far and decided to make my first mod, so here it is.

Civ: Celts
Leader: Brennus (Aggressive & Spiritual)
UU: Gallic Warrior (Swordsman with 2 moves, no Iron and City Raider I)

I used the data from the missing civ's thread.
This hasn't been tested much but it does load in the game and I was able to play several turns with it, enjoy and let me know what you think.

Just extract the zip to your mod folder.

The files over 500kb so I can't upload it and I have to go to class now; I'll figure out how to upload it later.

Ok, I split it up into two parts, here's part 1:

and part 2:

Nice work. Sadly I've never added a civ, but hopefully the Celts will get incorporated into a scenario or Mod.

Do you have the link to the thread you referenced? And thanks for posting this file!

Are there any new graphics in this mod (LH/UU)?

That UU sounds a bit over the top. You might want to consider reducing it's effectiveness a little.