Personally, I've never had a problem with shrinkage while hand washing wool sweaters, etc. with Dawn dish soap in luke warm water. Lay flat and let it air dry. This may take awhile.
The reason for the Dawn soap is that it is ph neutral and won't strip the wool. You can google "Dawn" and "Wool" and you can see what I mean. I've never had a problem, and once dry, there is no scent.