Resurrecting an ancient thread here, but my daughter recently bought a pre reg 208 tech line. I always where possible like to fit mud flaps, so I bought a genuine Peugeot set. Wasn't worried about them being fixed with rivets as I had previously fitted flaps to a C1 which were fixed using the same fastenings.
Fronts went on easy enough, remove one plastic retainer, fit through flap and press back into place. The remaining two fixings can then be marked and drilled with a 5mm drill. Pop rivets are the used to secure.
The rears however where a "mare" to fit. Again you need to remove one plastic retainer for the first fixing. Problem here is that no matter what I did, I couldn't get the clip to re-engage. Ended up using a similar but slightly longer clip I had in the garage. The flap then needs fixing to the wheelarch liner in three places and one further to secure the back edge of the flap below the bumper. The problem here is that the two fixings on the wheelarch liner edge are difficult to drill as there is nothing holding the liner in place so it moves as you try to drill.
In the end, I needed to pull the liner edge out from behind the bumper. I could then put something solid behind it so I had something that was then rigid enough to drill.
This is the first car I've come across where the arch liners are so flimsily mounted, particularly in an area where flaps may be fitted.