Hey,
A few people have asked me how to break out the hardcoded skins from the vanilla game models. Note that I am assuming that you know how to use the .xml necessary for adding the prop - or whatever you are doing - to the game. So I won't go into that.
The only tool you need is the havok pack - make sure you get the 32bit version!!! (need to register to download), http://software.intel.com/sites/havok/?page=tryhavok
Let's take the Apple Tree (1) as an example. I want to make it slightly darker.

The apple tree (1) uses the game model AppleTree_1.hkb
Fire up the Havok Preview tool, and open the AppleTree_1.hkb file by dragging it into the window and selecting "add for this asset.
Your program should look like this.

Next, click the menu File and select Save...
Warning! These next steps must be followed PRECISELY, or the program may not output what we want.
First, change Format to XML (Cross Platform Text)

Then click Browse. Switch "Save as Type" to "Havok Files (*.hkt *.hkx *.xml). Then enter the filename, ending with .xml

Then Click Save. Then click OK in the remaining tiny window.
Your .xml file should now be extracted at the correct location.
Open the .xml file and search for .dds or .png files. Note that some references are dead ends - you need to verity that there actually exists such a file in the Elemental folder before you change the filename. For example, AppleTreeCard3.dds clearly does exist.
In the example, you should locate the following lines (note that they will surely differ for other models - however the principle is the same)
<hkparam name="filename">C:/Users/DWallace/Desktop/Work/Elemental/Trees/Trees/sourceimages/AppleTreeCard3.dds</hkparam>
<hkparam name="name">␀</hkparam>
<hkparam name="originalFilename">C:/Users/DWallace/Desktop/Work/Elemental/Trees/Trees/sourceimages/AppleTreeCard3.dds</hkparam>
Now, change ONLY the filename to your new skin. For example, my new skin will be called HeavenfallsAwesomeSuperSkin.dds. I replace both references to AppleTreeCard3.dds.
Example:
<hkparam name="filename">C:/Users/DWallace/Desktop/Work/Elemental/Trees/Trees/sourceimages/HeavenfallsAwesomeSuperSkin.dds</hkparam>
<hkparam name="name">␀</hkparam>
<hkparam name="originalFilename">C:/Users/DWallace/Desktop/Work/Elemental/Trees/Trees/sourceimages/HeavenfallsAwesomeSuperSkin.dds</hkparam>
Now save the xml file you are working on.
Next up, start the Havok "Standalone Filter manager".
Select your file and click Load.

Then Click Done. DO NOT load multiple files at the same time, this will merge them and render them useless.
Next a tiny window appears.

Select Pick. Navigate to the location of your new skin. Press OK.
The next screen is a bit complicated. I will walk you through it (see numbers on screenshot below).
1. Select Write to Platform and click the Add button to move it to the Configuration Set.
2. Click the "...." button and select where your new file should be. Note that you should make the file ending HKB. Also set the options up below the "..." button like I have in the screen.
3. Click Run all Configurations. It should tell you what the screen says in text.

Then link your elemental mod xml to the new .hkb file, and Voila!
Old (left) and new (right)


A friendly reminder: Both skin and model must have UNIQUE filenames.