It's actually the agitation in the washing that shrinks the wool. If you just soak and spin out, you shouldn't have a problem. A front loading washer will also minimize the problem, because it doesn't agitate.
What a treasure!! I read a really neat article in an Australian quilting magazine a while ago that featured wool utility quilts called Waggas (I think).
From Patchwork Planet:
A unique Australian tradition is the wagga (pronounced wogga). Typifiying the Australian need to 'make do' with whatever was available, waggas were made of whatever the housewife could find. They are heavyweight quilts made of woollen suiting samples, or salvaged squares of wool blanket. Often a wool blanket was used for batting. The haphazard nature of the wagga is a result of the quilter patching anything suitable together, and gives waggas a wonderful charm.
http://inaminuteago.com/blog/index.php/archives/2006/04/18/does-anyone-have-a-clear-definition-of-a-wagga/ that is an interesting blog article about wagga quilts, too.
I think you could do neat things with your wool! I envy you!