wheel stud question

ive got a set of hubcentric spacers (that have their own lugs) that worked with my waffels but DONT work with my 96gt wheels.

The waffels have little indents inbetween each spoke that allows the cars lugs to fit in.
But the 96 wheels dont have this little space.

So i was gonna get shorter studs that allow my 96wheels to fit.

I did a search and i think that most people say that its best to remove the axles to swap the studs.

Im getting gears installed on wednesday D) and since they have to remove the axles anyway, i was just gonna have them install em for me.

Since i dont have time to order them online, will i be able to get shorter studs from a parts store and what size should i get?

thanks!

anyone?