If you do want to change the number of studs, the correct way to go about it would be to get new wheel bearings, new 5 stud wheel hubs and a set of rims all around. You would first remove the control arm and remove the old hub and bearing. Next install the new bearing and hub. Re-install the control arm and mount the wheels. Now, this is the short version. The whole job would take an experienced tech about 5 hours (Mounting tires to rims and then replacing 4 hubs and bearings). Needless to say, it's a big job and might not be worth the time or money.