[QUOTE=herman maire;5314032]If its on the rear, you will have to pull the hub, when you pull the hub you have to undo the CV, when you pull the hub the bearing gets trashed, so would need a new rear bearing. If its on the front its much, much easier.
I have to disagree! All the stuff mentioned above is absolutely unnecessary. (first off, remove caliper and rotor if rear wheel) Just get a BF hammer and smack the stud smartly several times. It will pop right out. If you have a steel lug nut available, you might thread it on the stud for a better striking surface. Get a new stud, slide in from the back, then use a hollow ended steel lug nut and some sort of spacers to "pull" the stud into place.
I replaced all the studs on my rear wheels with extra long ones to accommodate large wheel spacers, using this method. Did this 18yrs ago, and everything is still going strong! i.e. doesn't hurt the bearings or anything.
If its on the front, remove the front hubs, unbolt brake rotors, drive out the stud, and "pull" in a new one. The removal of rear bearings et all would be a nightmare solution to a simple fix!
Go to this thread and click on the link to photos in the first post. Great tutorial, but if replacing a stock length stud, there's no need to mess with the emergency brake stuff like he did. Nothing like pictures instead of words!!
http://forums.pelicanparts.com/porsche-911-technical-forum/252988-wheel-stud-replacement-pictoral.html