I have heard of using these for slot work. I just got 2 in the mail today. I have an Altinok that I was a bit unhappy with the slot. A couple of stokes with one and there was a world of difference. You can find them on Amazon and I think eBay. I also have heard that Steve at Vermont Freehand stocks them as "Slot Tools".

Just go easy. They are agressive and you could quickly ruin a slot.