I always ferment with the corn in I like the flavor better that way. That said many people do it the other way. I do a sour mash so I am using a portion of my corn over and over again. Try it one way then go the other way next time. The great thing about this hobby is a little trial and error never hurts. Long as you learn to make your cuts, and don't drink the first few ounces of poison you run, the sky's the limit. I would use barley or enzymes as the above mentioned. It would be a shame not to wring out all the sugar and flavor that corn has to offer.