Step 1: Testing the EL Wire
Plug both orange EL wires into the splitter and the splitter into the inverter. Connect the screw terminal block with the power supply.
Plug the cord of the power supply into an outlet. If everything works, the EL wire lights up as shown in the picture and you hear a high pitched sound. This is normal and comes from the inverter.
(If it does not work make sure to unplug the power cord first before you manipulate anything else.)
Step 2: Putting the Inverter Into the Junction Box
Cut holes on both ends of the junction box.
Insert first the screw terminal and then the connector as shown.
Putting the inverter in the box reduces noise and keeps the screw terminal dry (just in case).
Step 3: Connecting the Motion Sensor to the Power Cord
Make sure the power cord is unplugged! Cut it in the middle and prepare he leads as shown.
Pierce a whole into the rubber besides the screw and insert both cut ends.
Connect the big plug (that goes into the outlet) to L (brown wire) and N (blue wire).
Connect the small plug (that goes into the 12V adapter) to LS (brown) and N (blue wire).
You should now have two wires attached to N as shown on the plan and on the picture below.
Close the base of the motion sensor again and screw it in place. Make sure the rubber seal is still in place.
Step 4: Testing the Motion Sensor
Plug everything together as in step 1, and try to trigger the motion sensor.
The system should work like this (note the timer):
Step 5: Adding a Stand to the Motion Sensor
One way to achieve this is designing a custom add-on with Sketchup and 3D printing it.
Here's my take, feel free to use the files: http://www.thingiverse.com/thing:17055
Step 6: Installing the System
The sensor should be placed such that it's triggered by stepping out of the bed, but not by a low hanging blanket.
That's it! Thanks for reading.