I think most will tell you not to wash that top, but I had an antique one that frankly I didn't want to put on my LA dirty, so I stitched around the outside edges and soaked (NO agitation!) in the washer tub (I do not have a front load) using Restoration. I just followed the directions and did not spin it out. Be VERY careful getting it out of the tub as stitches can pull due to weight or if the fabric is not strong. I laid it out on a sheet of plastic with a fan blowing over it to dry.
If you are worried about the top falling apart by getting it wet, you can put into a laundry basket and then soak the basket and the top in the bathtub, using the basket to pull the wet top out . I machine quilted mine as I wanted it to be more stable than tying or hand quilting (at least mine!) would be.