Well, I bet this will be too long for a PM, so at the risk of threadjacking for a while I am going to let you know how I added units to my modules since you have mentioned having problems doing so in other posts.
First off, you really need to get inside that PAK. So
go here and crack that baby open.
Main reason you need inside the PAK is to find the precise nesting structure that is being referenced, otherwise you are horked from the begining. You'll want to open up the PAK for FfH, and also the 4 PAKs for Vanilla (lots of things will refer all the way back to this). I personally keep the 4 from vanilla packaged together and the FfH ones seperate, but you can easily place them all in the same spot, that is how the game sees it anyway.
Now, unless you are willing to just use the graphics that someone else has made, completely as they are, you will want to toy with things. So go and get
this program for skinning as well as
this program for fiddling with the model itself.
DDS is what all the graphics are in. So congratulations you can make buttons now too. Nifty side bonus eh?
Nifskope takes some getting used to, but there is actually a LOT you can do with it. Look at my new graphics for the Midas Flies for instance. I actually have little things buzzing around, and if you get them in a battle with another set of Midas Flies it really does look like a swarm of flies. All of that was through Nifskope really. The re-color that I did in the DDS doesn't even show up since it is so tiny.
One last file you might want for the debugging when things utterly fail is
this one here. Thus far I have used it twice and each time it revealed that there wasn't a problem on that end, but saved me a couple hours of worrying if it was.
Now, getting a model to actually work.
The important bits are the .NIF (this is the model) and the .KFM (This calls the actions, the actions themselves are just .KF). Ideally the NIF and KFM will have the same name and be in the same folder. But that would require that the animation be specifically for that model. Most of the models people make are done without unique animations because either they don't have the files to create them or because there was already an animation that did the job well enough.
You have to set up the XML in the
Assets/XML/Art/CIV4ArtDefines_Unit file to call the correct files. In general there will be both a *.NIF and a *_fx.NIF. The first is called as the <NIF> and the second is called as the <SHADERNIF>. If there is not a _fx.NIF, then you want to call the same file in both lines. Supposedly some models freak out big time if you don't do this redundant call, but I have seen numerous models work without a SHADERNIF line in the XML at all.
As long as the unit has been made, tweaked, and skinned to your liking by someone else, all you have to do is the XML part. So the only one of the files I had you download that is needed is possibly the unPAKer. If they didn't create their own KFM, or include the one they are working off of, then they should have told you what unit to use. You can either browse through the un-PAKed files for the unit pathway yourself, or go to the Vanilla XML and get the filestructure from their XML.
Also, another small thing that I am quite sure you are aware of, but many other people on the forum might read this and try it out so I want to mention, is that if you are grabbing files from another mod, you have to include it in a folder in the mod you are wanting them to appear in. Only Vanilla files and the Mod you load will be loaded up. So for instance if I want to use a unit from Age of Ice, I have to move the folder with the KFM and NIF into my mod that I am playing with, and it has to be somewhere inside the Assets folder (where precisely doesn't matter since you will tell the XML where to look). If you want to have the unit show up in the Civlopedia you will need to make sure that the .KFM has a .NIF by the same name in the folder with it (even if you don't use that NIF).
Now, if you want to modify the model it becomes more tricky. First rule is simple: RENAME NOTHING! The KFM file calls all of the .KF files, so if you rename those files, or move them out of the directory that the KFM is in, then you hork things up again. Now, with the KFM Konverter you can open this up and rename/redirect things, so THEN it is safe to rename bits and pieces, but I haven't actually tried this yet so cannot vouch for the safety of doing so. Main use for the Konverter should be if there are animations from multiple models which you want to make use of (I want the Warriors Attack 1, but I want the Swordsman's Attack 2 and the Chariot's Death...).
Now, the NIF contains a model and a skeleton, but they are completely colorless. The color (skin) is in the DDS files. That is what the DDS editor is for. I own photoshop and use that for my work, so I can't tell you much about the capabilities of that particular DDS editor sadly.
Been mostly just writing as I review the process in my head, but that should cover everything. I personally HIGHLY advise you use Modular Loading to test graphics. Then you have a single folder to run everything in and you will be able to easily isolate any glitches while you work out the filestructure and XML. All you will need is the UnitInfos to declare a new test unit (I call them SS in the description to make it easy to find in the Civlopedia), the UnitClassInfos since you are making a new unit, and the CIV4ArtDefines_Unit, which is where you will point it at the required NIF & KFM files (Plus the Schema file for each of them of course).