Ok, this is an ancient question but I'm going to add my process since it is considerably different.
First, I don't think I'm 'properly' conditioning the grain in terms of substantially hydrating it. Instead my goal is just to add a touch of moisture to reduce the dust and hopefully keep the hulls a little more intact.
I take a very small amount of warm water in the range of 8 to maximum 16 oz. That's for 25 to 30 lbs of grain (10 gallon all-grain). I'd stick to a cup for 5g batches. Then I dip my clean hands in the water and run my hands through the grain. I do this repeatedly until the water is gone. You will notice a change as you do it in terms of the amount of material sticking to your hands. I use this as a vague gauge of moisture content. A spray bottle would likely work just as well. I just like using my hands because I get feedback on the increasing moisture levels, something a spray bottle doesn't let you do.
Is this proper conditioning? I'm sure it is not but I get higher percentage of intact hulls, the kernels still fracture nicely, the grain is not so wet that it causes problems with my Barley Crusher, and the dust levels produced by milling are much reduced.
Some other milling tips:
- Don't grind flakes and certainly don't wet and grind flakes. You will only do this once if you make this mistake :)
- Don't grind inside: even with my wetting procedure, dust ends up everywhere.
- Don't endlessly expose yourself to airborne barley dust. Homebrew levels of exposure are probably not a problem but extensive exposure can cause occupational asthma.
- Don't grind near electric motors. There is a very very very small but real risk of explosion. Very unlikely grinding a 5 gallon batch but if you ground batch after batch in a small basement room and then ran equipment like a dryer...