from what ive understood, corn meal has the same pre emergent properties that gluten meal does.

Is there any reason for wanting specifically to put down corn meal or corn gluten. This time of year, most of your weed seeds have sprouted so the pre emergent attack isn't going to be that effective.
If you feel that your lawn is deficient in nutrients, you could try any organic lawn fertilizer or livestock meal (corn gluten, soybean meal, cottonseed meal, alfalfa meal, etc.) soybean meal has one of the highest Nitrogen contents. ALSO, topdress with compost as it has a wide array of nutrients.

Just remember.....it's going to take a couple weeks before you start seeing any proof positive results of your organic fertilizers. It also helps to remember that you're goal is to feed the soil and it's inhabitants, let them take care of your grass. you are on the right track keep it up! :)

The presence of White Dutch Clover in any lawn could be an indication of a lack of soil Nitrogen, but for many of us its presence is an indication of a diverse and healthy turf. The presence of dandelions could be an indication of a potential soil pH problem since dandelions do much prefer a lower soil pH then does the desireable turf grasses, although dandelions are known to grow in a wide range of soil pH's.
A good thick turf is the best way to keep dandelions from growing in your lawn and that good thick turf requires a good healthy soil.
What is your soils pH?
How much organic matter is in your soil?
What is your soils life (earthworms) like?
How well does your soil drain?
How well does you soil retain moisture?
What does your soil smell like?

At the risk of sounding simplistic and low-tech, how high do you mow? My yard was an oasis of green in a sea of neighborhood dandelions simply because I mowed with my blade set at the highest level. The first year I went around with a weed tool and pulled up the worst of the dandelions, but after that I seldom had any.