If you're not former military or federal civil servant you'll need a 5-day background check before you schedule your pick-up. Then you'll need to schedule pick-up with the GL agent/DRMO office.
Most importantly, get there early. I recommend showing up at 5:30-45a and standing in line. And remember to bring your vehicle's current registration into the Pass Office with you (sometimes they check, sometimes they don't).
Once you get your pass, go through the vehicle security check, and then take a right at the first light (where the vehicle inspection shed dumps you back into traffic). Don't go into the NNSY, you can't get to the annex from that gate and the gate personnel may or may not be familiar with where you're trying to get to. Call your GL contact for better directions.
Alternative: Contact BrutusM37 on here and see if he's willing to go grab your jewels for you. I don't think he's planning on being in the area much longer, but it's what I'd do if I was picking up from Portsmouth again. He'll charge you something...but it will probably be well worth it.