I have replaced the lower grille before. I think the only reasonable way to is remove the front bumper cover. It is a low risk job, just have to remove all the items in the cover (bumperettes, lights). Then there are some screws/bolts that hold it onto the car. Three on each side accessible high up in the wheel well, and then a few bolts in the middle right in front of the radiator. Only other detail is to carefully bend, and then rebend the tips of the black gasket which simply warp into the front of the wheel well.
Here is a DIY:
http://www.968forums.com/index.php?showtopic=6327
Again, removing all those 2 dozen little screws is a giant pain, I never even tried without removing the bumper cover. Bumper cover R&R is a straight forward job, pretty low risk.
Roland