You have to remove the hub/rotor assembly and press or pound them out with sledgehammer. Since you are replacing the studs, you don't need to worry about damaging the threads. However, if you do have to remove a reusable stud, run a lug nut down on the stud until it almost protrudes (so that you'll be hammering on the lug nut and not the stud). You put the new ones in much the same way you took the old ones out, by pounding them in. Lube the new studs and hub assembly well with regular motor oil to minimize galling and to ease installation. I strongly recommend that you DO NOT use a regular lug nut to “draw” the stud up in despite those who say they've done it successfully. They do make kits that draw the stud in the the hub like the lug nut technique, but I've never used one so I can't vouch for how well it works. I pound mine in with a hammer and a drift. MAKE SURE the stud is fully seated. You can tell it’s fully seated by the change in sound and feel of the hammer contacting the drift (its hard to describe but you'll know when you get there).
Happy hammering!!! /forums/images/graemlins/thumb.gif