Yes that is similar to what we do for egg yarn flies.
Yes chumming with corn would not be in the fly fishing ethical traditions, but heck thats what the salt water guys do to bring up fish in the blue water for many species. Chum, attract the fish and them throw the flies when they arrive.
BTW, heres another technique for carp which I heard has been used.
Dog food pellets !, chum with dog food pellets and then attach a pellet of dog food to a hook with a drop of super glue. I have heard this works but not actually seen it and of course being on the high road of fly fishing ethics I would not never use or advocate such a technique
When you come up with a dog food pellet fly though let me know.
Let me know the results of the hex nymph on carp, though. I have caught two this year on it while fishing for steelhead in one of our local rivers.