Customize existing keyboard layout
I'm not sure if I got you write. I have the problem, that I want some characters on specific keys on my keyboard. I use Spark to redefine this, this works for Terminal and GUI.

http://www.macupdate.com/app/mac/14352/spark

I also tried to redefine key under MAC, but this seems to be not so easy. So if you do not want to run an extra program, I cannot recommend you a solution.