The condition of the actual fabric in the quilt would greatly affect my decision on how much handling & washing.

Assuming that the fabric is in good shape; I would put it in the bathtub with cold water and a little gentle laundry soap and a color catcher already in the water. Then let it soak for a while and finally agitate it your hands. Drain and refill with cold water and agitate more until the water stays clear. Squish out as much water as you can without twisting or wringing the quilt. Roll it up in towels if necessary. Lay it out flat to dry if possible or spin it out in the washer and then put it in the dryer on a permanent press or cooler setting.