Here is a step by step tut on how to make Christof's chainmail upgrade have a transparent cape using The GIMP.
-First go into your main Vampire - Redemption folder located where ever you may have installed it.
-Find the Resources.nob file and open it with Winzip. Get winzip here:
http://www.winzip.com/ if you don't have it.
-Instead of unzipping the whole dang thing just go to classic mode and let's find the specific file we want.
-The image that represents Christof's chainmail upgrade is called Christof_Chain.tga located in 3d/Materials sub-folder of the Resources.nob file. Here's an image to help you:

-right-click the file name and choose Extract.
-Extract the file into your main Vampire-Redemption game folder like so...

-A 3d folder should appear. Go into that folder and into the Materials folder to find the tga file.

-Be sure to remove the Read-only tag on the tga file or we wont be able to edit it.

-Now open the file with The GIMP then switch to the selection tool and let's select the cape.

-Like before lets go into the Color to Alpha option.

-Some images require you to fiddle with the Color Picker to be able to get a transparency.

-Now we can just save the image. Be sure to use Save as... the first time you save this file.

-If everything went right, you should get this result:

That's pretty much how it goes. I think The GIMP is quite a simple tool for this kind of stuff. It is a very complete program for something that is free.