Can you take a damp white cloth to a very inconspicuous corner of the quilt and dab at it to see if you get any color transfer? If so, then there is no guarantee that any of the known solutions will keep the bleed from ruining the blocks.
You can try washing it using Synthrapol.
http://www.dharmatrading.com/chemica...detergent.html
This won't stop a bleed but will keep the dye from migrating to other fibers in the quilt. You MUST follow the directions completely, especially using HOT water. Also you need to have a washer that will give you loads of water. Energy efficient front loaders don't have enough water. So if that is what you have you may need to resort to handwashing the quilt in your bathtub so you have ample hot water.
Good luck!