i LOVE to catfish. I can tell you quite a bit. Now ive never done much line setting, mostly just poles.
What you need is Circle hooks. fair size too.
http://www.corefishingtackle.com/graphics/GamakatsuHooks/resize/GamakatsuHooks1alt.jpg
Circle hooks WORK. they take a bit of getting used to when pole fishing, if used on a line it wont matter to you. Catfish often take the food in their mouth and swim away with it before consuming it, as they swim away the line of course begins to tighten and the hook, being the shape that it is gets right into the jaw and hooks nearly perfectly each time. Ive used them for years. None of this Jerking to set the hook, tension is all you need. That is why the WORK for trot lines. sharper the better. Ive forgotten the brand i have but have used the ones above. they are laser sharpened and i cant stress enough, they do work.
Second thing is BAIT. forget livers and all that. what you want is what fish eat in their home waters. Here in KY river fishing in the OHIO shad are great, ive had great luck with bluegill. Im not talking about tiny ones, i used the biggest i could catch. (more on that later) You take your circle hook and set them right behind the back fin. if you have a flashlight hold it behind the bluegill so you can see the spinal chord, you DONT want to hook into this or your fish will be paralyzed. hook into the meaty part of the back not too deep not too shallow. IVe done this with great success. Ive even reeled them back in thrown them in the bucket and used them LIVE again the next week. (i used to have a small pond from lowes i stocked with gill so i could go cattin' whenever)
Like any other PREDATOR (catfish are predators) they will go for hurt fish, sometimes i would take a knife and just kinda scrape some scales off the fish or cut them just a bit (nothing lethal though) this really makes the bluegills attractive and stressed to the cats. that is what you want.
My best tips on catching bluegill are simple. get a cheap flyrod. some tiny tiny hooks. white 'poppers' are okay (look like a small octopus with red head white legs' my favorite item are (i cant recall the names) they are like mealworms but white soft bodies like maggots but larger. you can get them at any bait store usually. put those on small hooks. when gill fishing you dont have to throw them way out, no bobbers and all that crap. find a place where there is an old stump or something. you just have to slowly put the bait into the water, let it fall pull it up. often you will get an immediate hit. when you do, just flick your wrist and set the hook you dont have to really pull it or anything. fish on. This is how you do it guys, ive went places where people have been all day, and done this exact stuff and filled a bucket worth of gills in just a bit. often gills are sitting right next to the land, not way out there. ive caught them inches from land. The secret here is that bluegill will attack on instict when something hits the water, they always think its a bug that fell in. my neighbors small pond they will attack blades or grass or anything you just toss in. mimic this and you will catch bait.
trot lines hook them up on something solid, live bait, set them at dusk pick them up after dusk the next morning. full moons, rising waters are best times for cats.
guys i could go on and on, if you have specifics on catching catfish let me know.