I am kind of in the same boat that you are in but this is what I was able to intuit.
1 start with new brushes (I like non-serrated ones for this because it gives me more time to make corrections.). I wouldn't even bother to cut the com at this point.
2. Put the motor together and run the motor on a three or four cell pack for a min or two. (not as long as it takes to seat the brushes because it will be hard to see what you have done.).
3. Pull out the brushes and look at them. Where is the point of wear? (Big Jim says something about using a sharpie to make the old surface darker, I have had mixed results with this.)
4. If the hood is aligned the wear will be dead center in the middle of the brush (or evenly along the outside edges). If the wear pattern is too far in, out, up, or down then you have to bend the hood in such a way as to change the contact patch and move it over center.
5. Repeat steps 2-4 until the wear pattern is dead center. This is definately trial and error.
6. When all is as it should be cut the com, put in good brushes and wear them in all the way.
I hope this helps. BTW, if i am way off base on this someone please correct me.