It looks like it's less about "putting the fish to sleep" and more about simulating weeds with your fingers to avoid alarming the fish as you start to grab it.
Yes, you just need to work your hands into position and then grab it. I don't think that it's a good idea to do it if you aren't going to eat the fish, because I remember having to grab it very forcefully in the gills to be sure that it wouldn't slip away.
http://drowningworms.com/tickle-trout/