Here is what I did. I had to make a reverse lockout button for my T-56 Magnum....same principal as the Nitrous Arming button. I used the flat area to the left of my lighter plug. I made my button on autoloc.com. I had it in a week and its freakin cool. Mine is an off/on button 19mm with a red ring and the letter R in the middle of it.
When I do add nitrous at some point this summer, I will do the same thing. An arm button, purge button, open/close button. Take a look. If I can get a picture of mine, I'll post it up.