Hi from Greece, although i am not fluent in English i will try to describe shortly the procedure. (Of course there is a diagram in the box picturing the cable connections-its the easiest step)
installation is a very easy DIY procedure...i ve fitted them in our 4 family cars ...(vauxhall twintop, vauxhall gtc, honda HRv, vw polo....my up! was sensor-ready!!) The cost is about 30euros for the sensors (ebay or in any e-shop)....i bought the 2 sensors kit without the little monitor. (The twintop has the META system that fits around the licence plate-no holes needed. Its was a gift from the dealer but i made the installation myself. It costs here about 200euro). Of course there are other brands which cost more, but 4 years now i ve never faced a problem with any of them
You only need to measure the bumper and mark the holes. The sensors kit comes with a special "head' that you use with the drill and open the holes. Its much much easier than it sounds...Then you put the cable and the sensor in the hole and press it slightly. The only problem is if there is not enough space behind the bumper to place the sensor...(The GTC has something like a foam behind the bumper and i use a screwdriver to open a hole through the foam to pass the cable). Once you fit all the sensor you gahter all the cables and cover them alltogether with duct tape.
Then you find the hole that exist in the bottom of your boot (under the spare wheel) which is cover by a soft plastic cap and is used for draining the water (if something back there doesn't seal well...). Remove it, pass all the cable through the hole and then with the screwdriver press gently the center of the cap to open a small hole...then pass the cable through this hole and place back the cap. Seal then the hole on the cap with some silicon glue. You now have to find a place to put the sensors' unit, it comes with a two-sided tape and its easy to stick it everywhere...it has also the option to screw it (somewhere that is safe from the buggages).
the next step is to place all the sensors' cable on the unit (each cable has a number on it and the same number exist on the unit so as to place them correctly). You also place on the buzzer cable and put the buzzer where you like it, usually somewhere on or under the bases of the boots cover (I don' know the exact term...)
The final step is to connect the power cable. The sensors are powered by the R light. So you have to place the one edge of the cable on the unit and bypass the other one on the cable that power the R-light and you are ready!!!!
On the HR-V the installation was more difficult as i had to remove the bumber. It took only half an hour extra. The best solution is license plate sensors. They fit everywhere and you only have to crew the frame with the sensors and then place the plate on it.