How Should I set up my reel for catfish?

Your reel and line sound good and if your rod works for Alligator gar then it should work for catfish. For rigging I would recomend using a leader for your bait about a foot up on your line and enough weight on the end of the line to take you to where you want to fish and hold you in position. You might want to try some cut bait also for the catfish. Liver is good for the smaller ones but cut bait would be better if you want to catch some bigger cats.