I've actually never heard of basting the quilt back to the leader using a sewing machine. (but there's lots of things I've never heard of...) I pin my quilts to the leaders. There are lots of youtube videos demonstrating this.
You can also look into 'Red Snappers' a channel and tube system. Here's a demo:
http://www.youtube.com/watch?v=VdESb8_p5ec
Also, you can use zippers. You get pairs of long separating zippers. Sew one side permanently to the leader, then pin or use your 6mm basting stitch to afix your backing to the other zipper tape and zip them on.
Any of these methods are lots cheaper than getting another machine.