You wire it into a 6" extension. Just cut the red wire on the extension and solder the switches two leads to those. Then run that extension between your EI and power source. When the switch is off nothing should get through the red wire so the EI has no power to operate. Personally I use RCats Solid state switches. They're $25.00 and don't require a servo to operate.

http://rcatsystems.com/electronics/rc100.php