I remember someone on here buying/selling one for a MK4 Jetta and I seem to recall they were pretty simple to install .... but man was it ever expensive!
Why not get a reputable company to tint the windows? It would cost almost the same and it's so much nicer than some flimsy shade that needs to be retracted and pulled down all the time, plus it's a nice visual mod to the exterior of the car as well.
Just a suggestion.