For those who don't do them, here is the basic idea:
I hang from the smith machine with the bar all the way at the top. I also use lifting straps to help hang there. I place my feet on am incline bench so that my feet are above my waist. I then have my spotter place a weight in my lap.
At this point, you do wide grip chins witha slow controlled negative on each rep. You blast to the top and ease back down to the bottom. When your chin no longer passes the bar, give it an 8 second negative. I rest pause these for three sets.
The total rep range for all three sets is 15-20 reps.
Mine is usually 9/5/3 or something like that. I only break for 20 seconds between these sets.
Now I have gone past putting the weight in my lap, and I use a dip belt attached to a db. You can add more weight this way.
I promise that your lats have never hurt this bad before.