I sandwich my quilts with 505 basting spray. It is a temporary, washable spray that will hold the 3 layers together while you sew them.
I take my quilts over the the church and push tables together and my Dh helps me spray and sandwich them.
Let me look for a link I posted a while back about using a wall in your home to do this....
http://www.thequiltshow.com/os/blog.php/blog_id/2566