Sorry, I should have put your name with the quote.
Anyway, for the life of me, I can't seem to find this tool on homedepot.com or lowes.com, but here is a picture of the tool I used.

It works perfect for this, step on it, give a tiny wiggle to make the slot big enough for the wire, stuff the wire in, and give it a good stamp with your foot and you can't even tell it's there.