I wouldnt even bother with a lure unless the chicken dont work. If the cats been killing chickens you know what he wants no need to make it harder or more work for you. If the chicken dont work then you will need to move the trap to a new spot and change things up. At that point I would worrie about using lure and or bait. You can get a calling lure and use it above your set to call the cat in and then a gland type lure in the trap. You can use the calling lure then a bait in the trap. There are many lures out there you just have to find the ones that work best for your area by trying a few and see what works. Trapping lures and training scents are not the same thing get online and find you some TRAPPING lures both loud calling type and a good gland type. But like I said I wouldnt even bother with lures till you see if the chicken works. Here are just a few of the places that you can get lure from.
Pete Rickards, Briarpatch Lure, Fleming Outdoors, Grawe's, Hossier Trapping Supply, Leggetts, Dobbins Products.
There are about 100 more our there if you just take some time and look around online you will find tons.