Don't skip soaking and boiling the beans. Really. One type of protein present in beans--phytohaemagglutinin--causes extreme intestinal distress. The beans to be boiled to denature this protein; cooking them in a slow cooker or sous vide setup will not denature this protein and actually make things worse. If you're in a rush, use canned white beans; they'll already been cooked.
You can read more about phytohaemagglutinin here. So please, folks, soak and boil your beans.