Help reskinning monsters

[genmills]

The title says it all. Basically, I want to make a version of either monster that is much darker so it will look more like a silhouette. I would also like to get rid of that weird coloring when you look directly at it. You know, sometimes when you look at the monsters they get this purply color, similar to items that can be picked up...

Here is what I tried to do: I copied everything from the one monster folder, and made a new folder for my monster. Then I renamed everything inside to the name of the new monster. Then I opened up the .dds files in GIMP and changed them to be really dark. I also tried altering the .mat file to use the new darker .dds that I made. I also used the model editor to have the .dae file use the new darker .mat, and I used the model editor to alter the .ent to use my new darker .dds/.mat, but nothing seems to work. No matter what I do, the new monster is the exact same color as the old one.

Could someone please explain the process of reskinning models? I don't need detailed explanations, I just need to know every step to learn what I am missing. (e.g., you don't need to say, "Open GIMP and import the .dds and change the colors this way, etc, etc." Just say, "Darken the .dds file.") Thanks so much!