I'll second what has been said above, stud conversion kits are designed primarily for people who autocross and/or track their car with dedicated autocross/track tires and wheels who change them often and need to change them easily and quickly. Who cares if the black anodizing is scuffed, they're not for looks.
I bought our stud conversion kits from Motorsports Hardware, owned by a friend of a friend. I put a couple drops of Loctite Blue 242 on the threads, hand tightened with an Allen wrench, waited 10 minutes and then put the wheels on. From the Loctite website
Technical Data Sheet for Blue 242:
Sets in approximately 10 minutes and fully cures in 24 hours
This is what I use on my car and my wife's car:
I use it with my Ryobi 18V 1/2" impact wrench. It works great and the protective sleeve protects the wheel. Based on the info here maybe I'll throw one in the trunk for possible future encounters with impact wrench monkeys.
Regarding Discount Tire, I can't believe that they didn't have a breaker bar in their shop that they could have used.