Pictures would be wonderful!
It can be washed in a top-loading washing machine as long as you never allow agitation. I would probably use Orvus for soap. Fill the machine with cold water, add the soap and mix it in, stop the machine, add the quilt, hand agitate by pushing up and down, move knob to "spin" and allow soapy water to spin out, allow it to fill with rinse water, stop the machine, hand agitate by pushing up and down in the rinse water, advance to "spin" again. Probably do two rinses.
Take out immediately and either lay flat to dry or dry in a large dryer. If laying flat, you can do it outdoors as long as it is in the shade, you place a large sheet underneath, and you cover the quilt with another large sheet (to protect against passing birds, etc.) and anchor the sheet edges with rocks.
Maybe the first question I should have asked is does it really need to be washed? Is it stained? If stained, I would probably use Retro Clean (
http://www.retroclean.com ). If there is any possibility of color bleeding, I would use Synthrapol (but that requires hot water).