I did not get a security package per se. My dealership installed the locking lugs and returned the four replaced lug nuts to me. From your question, I gather that your GT came with the locks already installed--the way my '03 Cobra did.
As for the security hardware. click the following link:
Cruiser Accessories | Welcome to Cruiser Frames Click on "Hardware" at the top. Look at the bottom two items shown. Or, go to your auto supply and ask. They are part # 81330 and 81230. I used the screws with machine threads and self-locking nuts. The other style are shorter and have sheet metal threads with inserts. I drilled and tapped/threaded the license plate location rather than use the nuts. (Instructions for drilling/tapping/treading available upon request.)