From what I've seen about socks, each needle does not have to have the same number of stitches. I would do one of two methods:
11-10-11 stitches for needles 1-2-3 respectively
10-12-10 stitches for needles 1-2-3 respectively.
I haven't made any socks yet, but I've read lots about it. Lets hope an alpha sock knitter comes along.