Create Textures

[DRedshot]

Easy, Simply copy the entire grunt folder (to desktop), edit the .dds file in the duplicate and rename the folder to whatever you want!
Then remember to put your folder back where it came from (entities/enemy)
And also remember to put it in your custom stories folder like this:

"custom_stories/YourStory/entities/enemy/YourMonster/"

^- That is the easy option.

The alternate way is to import the grunt's .dae into your 3d modelling software, and change the colour filter on the material to your custom .dds file. However, this way MIGHT require you to do the same to all the animation files, i'm not too sure... The only good thing about doing it this way is you can keep it in the same folder as the original grunt, so it saves memory. Apart from that, I'd just stick to the top option.

EDIT:
I focused on the grunt example, but the same can be done for any other item, in fact it's easier, because they don't have to be put back in the same folder they were taken from. I always put monsters in the enemy folder, just to be sure they will work, but you can probably put the grunt wherever you want too.