I've done this Mod, try this link to our UK Boxster forum. (BoXa.net)
http://www.boxa.net/forum/index.php?showtopic=47899&page=6
I have since taking this video changed my rear lights back over to a set of LED's and the 3rd brake light is much more brighter and quicker now I will post a short video later when I have time.
Guvs
note:
I forgot to say scroll down it is on post number 158.