Here are some step by step instructions.
http://www.realtime.net/~rentner/Porsche/Radiator/Radiator.html
I followed these during the winter when I decided to touch the chips in in comfort and warmth this winter (so the bumper cover sat in the lounge for a couple of weeks - nice to have an understanding girlfriend!)
The only difficulties were that:
Once I had undone everything the bumper still felt fixed on - it wasn' t (I found after several exploratory tugs...!),
Putting it back on at first it just did not seem to fit! The reason for this became clear after far too long - the rubber radiator ducts need to be aligned by a second (or preferably third!) person. Otherwise they interfere with the bumper cover sliding back on.
Apart from that it was no great problem. Some of the clips were not quite as described, but this might vary from year to year. With these intructions as a guide everything seems to be easy to find. Good luck!