Has anyone had any experiece with the BergWerks Keyless Entry system for the W124 sedan, 92 year model? I would like to know any warnings or praises before I buy this, and I would also like to know if it is moderately simple to install. How comprehensive are the directions? I don't want to mess up something by wiring something wrong.. Do you think it is worth it just to have my local shop install it? They have worked on many Mercedes' before. Thanks!

- Matt