I don’t know much about that stretch, but:
If you’re going to be chasing channels (you’ll probably get much more action), I’d find some big sucker minnows and hack them in half. I’d then put half of one on a 4/0 or so Gamakatsu circle hook. As far as what to attach that too, I’d go with some 50-80 lb Power Pro (you don’t need that heavy of line, but if you hook something big, you’ll want it) or 20-25 lb Trilene Big Game. Slide on a 2-3 oz slip sinker (depends on current, I like No-roll type). Then, a barrel swivel and a 8-12 inch leader to your hook. That should fit the bill.
If you want to try for flatheads, I’d go with the 80 lb Power Pro, a 10/0 Gamakatsu of Kahle hook, a 3-4 oz No-roll sinker, and shorten your leader to 6 inches or so. Then go with a lively bullhead for bait.
Look for current seams and snags and holes. NOt knowing that stretch of river, I can’t really tell you exactly what to look for, but cats will tend to hang out near the edge of some nice current to bring food their way.
Have patience. If you’ve never fished cats before, it is tough to place a bait and not touch your rod for a half hour, but sometimes you have to do that or wait even longer.
As far as gear, heavy bass gear or musky gear will fit the bill for channels, but it is generally ideal to have a softer, slower tip (a must for circle hooks). For flatheads, musky gear will get you by, but it is not ideal. An Abu Garcia 6500 is a bit light in most people’s opinion. Something the size of an Abu 7000 seems to work well with a stout rod (something as thick as your thumb at the base is not overkill). Again, you don’t really need a fast, sensitive tip, but you’ll need some power.
That should get you started. Of course, I can’t seem to catch a flathead, so take my advice with a grain of salt.