You may just have to cook them a little longer.
Or, you could try this quick soak method (I have done something similar to this before):http://localfoods.about.com/od/beans/qt/soaking_beans.htm
Another no soak method (I have never tried this):http://thepauperedchef.com/2009/06/90-minute-no-soak-beans.html
ETA: yesterday morning, I had the greys in the kitchen unsupervised while I ran downstairs to get my laundry before work. I came up to find my CAG eating my soaked (but not yet cooked) beans. I'm not sure how much she was eating and how much she was just throwing around, but she was having fun!