You have your guitar string doubled, right? Push the bent end through the bury and pull the end of the zing-it back through. Remember to taper the end of the zing-it before you put it through the loop in the guitar string.
Not being a guitar player, I usually use a piece of network cable. Untwist one of the twisted pairs in a Cat5 (or so) cable to make your fid. Leave the insulation on the wire.
I hope I've understood your question correctly. Let us know how it goes.