On sanforized pairs, the shrinkage is minimal with a cold wash and hang dry, though in my experience you will typically see the inseam shrink. If you hang them by the legs (with the waist closest to the ground) I'm told it will minimize this shrinkage. If you're really worried about the length (as in any change will result in high waters or whatever), I would recommend what @gaseousclay said, do a cold soak with minimal agitation and then hang dry for the least shrink. Most of the shrink on a sanforized pair will come back out with wear, and this stretching back out process tends to happen faster the longer you've been breaking them in -- after about a year my American Sixteeners still come out of washing tight, but they're back to normal after a couple hours of wear. Supposedly you can hang them upside down or weight them to pull the length back out, though if you're going for fades I can't imagine this is good for helping them set.
@justinkapur I compeltely agree with these suggestions if you're trying to keep the inseem length where it is