Firstly, just verify that we are talking about studs here, the things attached to and poking out from the brake disc. These are on a spline shaft, so they don't loosen. You hit them out with the biggest hammer you can find.
The wheel nuts are the ones you loosen to get the wheel off.
I replaced my studs myself on a Nissan 1 Tonner. It all depends on how much access you have to behind the brake disc. If you can get the studs in and out from behind the disc, it's easy.
1) Klap the old ones out from the front. Remove them from behind the disc
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2) Clean and lube. That copper compound is great.
3) insert new ones from the back of the disc.
4) I actually used an old wheel nut to pull them through into position. Put the nut onto the new stud.
5) The studs is not threaded all the way down to the disc, so find some sort of spacer to put between the disc and the nut. I think I used an old socket which was lying in the garage.
6) Tighten the nut down onto the spacer, and it should pull the new stud snugly into place.
Note: If it requires excessive effort, there is a risk of stripping the stud and/or nut, which is why I used an old nut. This is where good lube is useful.
It isn't a difficult job for a shop. They would probably have better tools too. If the labour works out to 300-400 for all 4 wheels, I wouldn't even bother doing it myself.