Just find the smallest Allen (sp) wrench possible, that should do the trick. Also next time your at the park, try one of the big pin locations like Store Command or Bonanza Outfitters, I could only guess that they should have extra stuff laying around.
I haven't got a clue what the intial poster is talking about and I collect them damn pins!!!
Locking pin backs are small, gold tubes that slide over the pin's stem; here's a photo. There's a tiny screw built into the side of the pin back that you tighten down to clamp onto the pin's stem. They provide a VERY secure lock, ensuring you pin will not accidentally come off. Unfortunately, the stems sometimes poke out through the end, scratching you, others, or other pins you happen to be wearing. They also pinch and/or chew up the stems if you clamp down too tight.
I'll never use them again; a fresh, rubber pinback is still the best way to go.