how do you make a dual layer blu-ray fit onto a single layer disc
BD Rebuilder. Make sure to install the necessary programs to go with it. All are free to download and use, other than AnyDVD HD, which is necessary to rip the blu ray to the hard drive.
Hope you have a lot of room on your hard drives and a fast computer. Even with a Core2Duo dual core processor you may be looking at 14-16hr encode times.