using an old bag as an underquilt

Can I use a 15 year old sythetic insulated bag (Sierra Designs Northernlite) as an underquilt? If so how could I rig it up?

Check out the underquilt section of this forum. (it's towards the bottom of the forums page).

I bet you'll find something there.

Cut it into a rectangle, put a drawstring at each short end, put grosgrain or ribbon loops on each corner. Attach the loops to the hammock support with shockcord. Done.

There are pics, and threads with instructions, here and in the whiteblaze hammock camping forum.