I do the normal gunslinger around my index finger and the reverse around the middle finger.
I use the same grip for both, which is with the palm of the hand facing to my body, the ken hold between the middle and index figers, string to the inside.
I'll see if I can post a photo of the grip later on today.
Edit: Re-checked the other thread. To me it does not look like the movement of the gunslinger backwards, it is quite different.
If you have ever done pen-spinning, it is like doing thumbaround and then learning reverse thumbaround. Looks like the trick is just reversed, but they are different tricks.