I'm going to make a small correction to what was said here... For controlling two sounds you can't just go to any ground on the kit. At least the experience I have had with crix's kit you either need to run one wire from the middle terminal of the switch to the battery ground or two wires from the middle terminal on the switch to each ground for each sound the switch is going to activate.I could use a hand with the same problem. I have the Crix sound board ( the square one with screw terminals) and cant get two sounds on one DPDT. I'm going for startup with hum when toggled on and shutdown when toggled off. So far no luck even with reasonable electronics experience.It's not too hard. With a DPDT, just think of 1 row of 3 terminals as 1 switch (lights), and the other row as a 2nd switch (sounds).
So let's say, we'll make the left set for your sounds. You're gonna run 3 wires from the sound board to the switch. The middle terminal is gonna be connected to any ground terminal on the sound board. Then the upper and lower terminal are run to the startup and shutdown terminals on the soundboard.
Now, the "active" terminal is the one opposite the way the switch is thrown. So if you flip the toggle up, the middle and bottom terminals are connected. Flip it down and the middle and upper terminals are connected.
So if for you flipping the toggle up turns on your pack lights, wire the bottom terminal to the startup sound and the upper terminal to shutdown.
I personally just ran the one wire to the battery ground terminal made things easy.