I was experimenting with a memory editor (Cheat Engine), and discovered that the .DDS textures used are stored uncompressed in memory. By pasting the data for one texture in the place of another, you can have any dds texture and have it replace any that is in the game. For example I changed the texture for a Horse mount, into a zebra texture. The zebra texture can only be seen on the one's person screen, and is not sent or stored to the server. This is a quick and dirty version, as it is not UV properly, and only one of the horse's 3 textures was replaced (and not the bumpmap or alphamap things, but it would too I just was busy with final exams)

I bet a quick program that uses memory pointers could be easily made to paste the textures in, however I do not know any programming languages.

BTW the mount was enabled using the SetMount function in an LUA script on the server pack.

Heh. Very cool

Indeed, that is pretty cool. I wish my brain worked like that