I use masking tape to hold the quilt back to the wall, wrong side facing me. I use my hallway, because it's the only open wall space large enough. I tape the top then the sides, letting gravity show where to smooth out any wrinkles.
I use Sulky's KK 2000 basting spray. Although it says it's odorless, I do detect some smell and need to open a window or go outside after using it. However, it's one of the only basting sprays that says it's non-flammable, non-toxic, and ozone friendly, even though there are still warnings about keeping away from sparks or puncturing the can. Some of the other sprays on the market say things like highly flammable, explosive, etc, and who wants that?
I spray the backing lightly, and then smooth the batting in place. It's important to put down newspapers under this, as any overflow of spray will fall to the floor. I don't think it would be too damaging, but your feet get sticky walking through it until it evaporates after a few days. (How do you suppose I know that?)
Then I repeat the process, spraying the batting and smoothing the quilt top over it. This method has given me very good results with up to twin size quilts, keeping all the layers even. It is a temporary adhesive, though, so you need to do it no more than a day or so before you start quilting. Once you've put some of the basic quilting in to hold it all together, it doesn't seem to matter if the spray starts to lose some of its grip.