I made my own barley crusher, so has it quirks. If your talking about malted wheat, I crush it pretty small. Smaller than barley.
I take my barley and spread it out in a plastic tub and spray it with a few squirts of water in a spray bottle. I flip it around some and squirt it again. I try to look for uniform wetness. Go sparingly at first. As time goes on, you'll learn how much to use. Your looking for kind of a leathery husk. It can get sticky going through your mill if you use too much. I would do a small amount and see how it works, then you can adjust the rest of your grain. You will have a nice crush and your hulls will look like shucked corn.
Don't do the wheat! It has no husk and will certainly make a mess
Raw wheat I grind pretty fine like rocky flour. Wheat flakes can be added without any preparation.
Good luck and happy brewing.