I've done 4 or 5 gill cuts, two were "good" as in a near total success; the others were less "good". The reason some of the operations did not work out is that the gill curl had either already gone into the gill plate, making the curl permanent, or else I was too conservative in what I cut and did not take off enough of the gill membrane.
I may have a small bottle of Transmore kicking around somewhere if you want help with the operation.
Below are a few photos I dug up of past operations I did.
Depending on the type of gill curl your fish has, you may decide to cut vertically or horizontally:
A horizontal series of cuts will look like this:
A vertical cut will look like this:
The fish in the above photo looked like this when seen whole:
If the fish looks somewhat familiar to users of this forum, that is because it belongs to Mike aka Exoticaquaria, a sponsor of this forum!
Mike caught the fish and used a bag and large container to hold it:
Then it was onto the operating table:
After the operation, which took about 15-20 seconds, it was back into the tank with the fish; note how the fish' head was positioned by outflow of filter to force oxygenated water into its mouth and through its gills:
As you can see in this photo, Mike and I decided to go with the horizontal series of cuts:
As you can also see, the gill plate itself was pretty severely bent:
Looking back on this operation, I think we should have cut off the whole gill mebrane with a vertical cut, but even then, due to the severe bending of the gill plate itself, the "look" of the fish would still probably not have been improved that much. I am sure Mike can post some up to date photos of this fish.