When I was in WDW in March people were even trading out of their pockets - especially with CM's - Don't Sweat It - enjoy yourself and above all HAVE FUN!
You can use any lanyard you want. If you don't want to wear something around your neck you can ping them to your backpack or purse. People do trade from there pockets. I'm a ex-cast member and have seen just about every type of pin trader. The ones who carry around suitcases full of pins to the pocket traders.
Just have fun and enjoy yourself, don't worry about what type of lanyard you do/don't have. Hope you have fun and get some nice pins.