If you search enough in 2014-2015 threads you can find all the info you need, mostly in this thread:
Porsche Headlight Retrofit [from CAD, prototyping to finish)
Particlewave has been very helpful and instructive on this. I think he made these videos:
Taking the headlight apart:
https://www.youtube.com/watch?v=-sjOnfMHED0
Putting it back together:
https://www.youtube.com/watch?v=Rz515L_QDFg
The part that you want to do is somewhere in between those videos and does not involve adapting a HID. Easy.
The tabs that hold the innner lens in palce are probably VERY brittle and likely to break. I'd recommend just swapping the "clear plastic outer shell".