How to mirror textures on body parts like biceps and triceps?

I think it's too simple to be a tutorial. :l

http://forum.toribash.com/showthread.php?t=109294
http://forum.toribash.com/showthread.php?t=166679
http://forum.toribash.com/showthread.php?t=200994
Brought to you by a simple Google search. Please do that next time before asking your question.