I simply put it on the right slide lever and that's it. I can hit it at anytime, and apply what brake I need. I can also set the brakes full on for engine starts, etc.

I've never tried doing the snap button thing so I can't off the top of my head explain the programming you to do that. However, using a P-Mix set to "Origin", you can make the right slide lever work Aux 5. The manual explains how to do that.

I use the right lever since once I'm pretty well on the ground I can keep steering with my left hand and use my right to hit the brakes.