Hi my brother has a JT 5.0. You program it by holding the top or the middle button down for about three secounds and then it will show a blinking line and you can write what you want. You change the letters by pushing the bottom button. You submit it by pushing the top or the middle button on your grip. and every time you click your gun the greating comes up.
I hope I helped you a little. (try expirimenting a little with the top and the middle buttons, but I am pretty sure it is the top.)