Looking at pictures, it would probably be easier to pull that off on a roadster. On a coupe, the bootlid lip is already much higher than the fenders.
The Hamann spoiler below curves straight down. The TKR spoiler curves back up and then down.
http://i01.i.aliimg.com/wsphoto/v0/3...LER-b-font.jpg
http://preview.netcarshow.com/Hamann...006-800-0a.jpg
It would most likely need modification to fit regardless. If you end up putting it on, make sure to post pics.