birdie:
You're thinking of the "static cord" method. You take the sheath, with cord at top and stuff it into your pocket. The cord sticks out of your pocket and is attached to your belt. When needed, you grab the knife handle and pull it out of your pocket, taking the sheath along. When the slack in the cord is taken up, the knife pops out of the sheath and the sheath is left dangling from your belt. You need to adjust the cord length for best results.
My preferred method is something that I saw someone do with a Nealy custom - might have been Nealy's idea, might have been the user. Anyway, you pull your pocket inside-out. Take a heavy-duty safety pin and pin the top of the sheath to the inside bottom of your pocket (using one of the holes already on the sheath or drill your own), then push the sheath into your pocket. When needed, grab handle and pull. Pocket material acts as static cord and you are left with knife in hand and sheath dangling from pocket. I like this method because you don't have to mess around with a cord, and because it's completely invisible until needed.
