They can be ripped using an old PS3 (old, clunky, hard to find), an Oppo 103 or 105, a few Pioneers and a few Sonys. The mother lode for this info is on computeraudiophile.com although there are similar but less comprehensive threads on other forums including here: SACD ripping with Oppo or Pioneer
In addition, my MITR column in the September Stereophile has an overview.