I'm not sure if the studs are replaceable, I can't say I've ever tried to.
If they are you'll have to remove the hub from the knuckle and probably the brake rotor. They aren't like a car, the rotor is bolted to the hub on the backside.
I've never had to replace the factory studs but i have them in my parts kit just in case. I've had to swap multiple studs in my superatv wheel spacers and I had to match those up at a local parts store.