I use woolen clothing a lot in my quilts. One thing I have found useful is to cut the garment into large pieces (basically taking out all the joins/seams) then wash. Some fabric shrinks a fair bit, but I have cut up skirts and jackets that have had minimal/no shrinkage. With the seams/hems and whatnot cut out you will get maximum shrinkage and after washing/drying/pressing you will have usable fabric which will pretty much withstand everything.