It is very involved and VERY expensive. There are over a thousand dollars worth of parts alone.
There is a magnetic field sensor that must be installed in the roof and the US roof has no provision so one must be fabbed. In adition, the sunvisors must be heavily modified to clear the console and a multiple wire harness must be built to travel between the magnetic field sensor and the compass.
It is indeed a novelty but I would not do another myself.