Determine the best location for your siren. Protection from the elements is important if the unit is not rated weather proof. Typical locations can include under roof eaves or just inside the front door if a discreet location is desired.
Disconnect the electric at the fuse box and verify that the power is off by using a circuit tester. If you have a 12v system or plug-in system, simply disconnect one of the leads or unplug.
Mount the siren(s) noting the manufacturer's instructions and make sure access to the terminals is available.
Run your wiring from the appropriate terminal on the console to the siren and connect, making sure that any bare wires (especially positive ones) are not left exposed.
Test the system with a helper outside to determine if the placement and volume adjustment (if possible) are sufficient to alert those nearby.