It's really simple.

-you use a switch and a servo a mount it on a board and forget about it.
-you keep a spare AA battery with you
and that's it!

You can activate it by one of three ways:

-you can mount a small switch outside the plane (be creative and nobody will know it's there)
-activate it with a servo switch on you transmitter
-slave it to the throttle (remember to take the battery out or leave the engine throttle open.

I think for most people the easiest and coolest would be to use a transmitter switch.